AS STATED BELOW IN DETAIL, THIS IS JUST SPECULATION, BASED ON SOME GUESSWORK AND PRECEDENCE, AS WELL AS SIMPLE DEDUCTION AND ELIMINATION. NO INSIDER KNOWLEDGE IS INVOLVED.
Assuming that Pokemon is due out this year for the Nintendo Switch, we are rapidly running out of time for Nintendo to actually announce it. There are indications that the game is coming out this year (it's the only one of the Switch games that have been announced with nebulous release dates which has a concrete "2018" attached with it; the anime is almost done with material from the Gen 7 games; the last Gen 7 Pokemon has been revealed, so there's nothing else left for Gen 7 at this point, short of another surprise mid-gen addition like Zeroara was)- but there's still no actual concrete word Pokemon is coming this year.
My theory is, assuming that Pokemon is due out on Switch this year, could it be getting announced within the next eight days? Now, this might sound like a rather dramatic idea without context, but there are reasons to speculate that might be happening. Given that Nintendo's financial report is April 26 and that they will need to outline their planned lineup of games for the year in their report (at least from the games that they have actually announced), what are the odds that, assuming Pokémon is this year, it is announced before then, even if the announcement is as facile and empty as Sun/Moon's original announcement was? I mean, of course, nothing stops them from "2018 or later"ing it again in their financial report and just announcing it later, but still, it is an idea to consider, especially given that there is a free slot on the Japanese Nintendo Direct archive (and that a Pokemon Direct was removed from the page to free up that slot). If Nintendo plans to actually assure investors of how they plan on selling 20 million Switch units this year, then announcing that they have Pokemon and Smash hitting this year will be the easiest way to assure them of that idea- but unless they want to actually announce the game's release date via an investor briefing, it would be to their benefit to make a consumer facing announcement via a Pokemon Direct ahead of time then as well. With Zeroara's announcement now out of the way, and no more Gen 7 considerations, the way is clear for them to announce Gen 8 at last, too.
It is also important to remember that we are really far into the year now- while Pokemon games have previously been announced as late as May or June, they have been remakes and re-releases like ORAS and USUM, never a new game entirely. It is also important to remember that new mainline Pokemon games have thus far never debuted at E3- The Pokemon Company usually likes to do its own thing. All of this suggests that we are due for an announcement sooner rather than later- and sooner, well, Nintendo and TPCi would probably want to do it asap so they can commit to the date to Nintendo's investors too.
To be clear, the lack of an announcement in the next eight days doesn't necessarily mean that Pokemon isn't coming this year. As noted already, Nintendo can just "2018 or later" the game again, and announce it at a later date- but as noted above, beyond April 26, precedence makes the pool of possibility for the game to be announced and subsequently released this year smaller and smaller.
TL;DR: I think that Pokemon is due an announcement within the next eight days. If it's not announced by April 26, the chances of it releasing this year drop dramatically. I also think that it is in Nintendo's best interests to actually get Pokemon out this year, because right now they are sorely lacking in mainstream titles to keep the Switch's momentum going- as big as Smash is, it alone cannot carry the system for the entire year. That is, to me, another consideration for why Pokemon will be this year, and why, as a result, it will be announced within the next eight days.
Assuming that Pokemon is due out this year for the Nintendo Switch, we are rapidly running out of time for Nintendo to actually announce it. There are indications that the game is coming out this year (it's the only one of the Switch games that have been announced with nebulous release dates which has a concrete "2018" attached with it; the anime is almost done with material from the Gen 7 games; the last Gen 7 Pokemon has been revealed, so there's nothing else left for Gen 7 at this point, short of another surprise mid-gen addition like Zeroara was)- but there's still no actual concrete word Pokemon is coming this year.
My theory is, assuming that Pokemon is due out on Switch this year, could it be getting announced within the next eight days? Now, this might sound like a rather dramatic idea without context, but there are reasons to speculate that might be happening. Given that Nintendo's financial report is April 26 and that they will need to outline their planned lineup of games for the year in their report (at least from the games that they have actually announced), what are the odds that, assuming Pokémon is this year, it is announced before then, even if the announcement is as facile and empty as Sun/Moon's original announcement was? I mean, of course, nothing stops them from "2018 or later"ing it again in their financial report and just announcing it later, but still, it is an idea to consider, especially given that there is a free slot on the Japanese Nintendo Direct archive (and that a Pokemon Direct was removed from the page to free up that slot). If Nintendo plans to actually assure investors of how they plan on selling 20 million Switch units this year, then announcing that they have Pokemon and Smash hitting this year will be the easiest way to assure them of that idea- but unless they want to actually announce the game's release date via an investor briefing, it would be to their benefit to make a consumer facing announcement via a Pokemon Direct ahead of time then as well. With Zeroara's announcement now out of the way, and no more Gen 7 considerations, the way is clear for them to announce Gen 8 at last, too.
It is also important to remember that we are really far into the year now- while Pokemon games have previously been announced as late as May or June, they have been remakes and re-releases like ORAS and USUM, never a new game entirely. It is also important to remember that new mainline Pokemon games have thus far never debuted at E3- The Pokemon Company usually likes to do its own thing. All of this suggests that we are due for an announcement sooner rather than later- and sooner, well, Nintendo and TPCi would probably want to do it asap so they can commit to the date to Nintendo's investors too.
To be clear, the lack of an announcement in the next eight days doesn't necessarily mean that Pokemon isn't coming this year. As noted already, Nintendo can just "2018 or later" the game again, and announce it at a later date- but as noted above, beyond April 26, precedence makes the pool of possibility for the game to be announced and subsequently released this year smaller and smaller.
TL;DR: I think that Pokemon is due an announcement within the next eight days. If it's not announced by April 26, the chances of it releasing this year drop dramatically. I also think that it is in Nintendo's best interests to actually get Pokemon out this year, because right now they are sorely lacking in mainstream titles to keep the Switch's momentum going- as big as Smash is, it alone cannot carry the system for the entire year. That is, to me, another consideration for why Pokemon will be this year, and why, as a result, it will be announced within the next eight days.