The common guess is that the Switch version will follow the "classic" formula: no open levels, different multiplayer implementation.
Rest should be mostly the same as 5th gen (World): better UX with streamlining of some features, mostly the same movesets, same "rules", etc.
Development of MHW started around early 2014 (a bit more than 3 years before the E3 2017 reveal). Back when supposedly they asked Nintendo for more RAM in the Switch.Correct me if I'm wrong, but production for World started at around the time before the Switch came out, right? Not to say that as the excuse, but if you don't know why kind of tech the system is using, it would be kind of difficult to build the game for it when you were more focused on PS4, Xbox One and PC, wouldn't it? Mind you that the sooner we get to August, the better since World is starting to slow down hard on me and going into Generations Ultimate will be fun to experience again with new monsters.
Of course with all that said, I think we know that Capcom wasn't going to outright abandon Nintendo and the Switch. It will be interesting though to know where the series will go next (although in fairness, we probably won't see that anytime soon if World is off the table there). Still, can't wait to see where the series go next.