It's hard to justify putting out a new MK soon when MK8DX still charts every single month. Unlike the two games during the console/handheld split, these would directly cut into each others sales. Why cut its sales potential when MK8DX is on track outsell every single entry except for MKWii? Yes, MK9 would sell and yes it would boost hardware sales as well but it's also the perfect opportunity for the MK team to try something new that could potentially benefit them more in the long run. They did try with ARMS, no reason they can't do that again unless their hardware roadmap requires them to have a new one out soon.
Nintendo as a whole has recognized the importance of new IP and revitalizing old IP with new ideas and they will continue pushing for that.
Splatoon is an interesting case because it's an example of a game performing disproportionally better in Japan than the rest of the world. They will definitely ride it out with Splatfests and special promotions for as long as they can but the franchise can go so many directions after that. I don't know if it makes sense for them to make a Splatoon 3 that would inevitably split the fanbase, something they probably want to avoid after introducing Nintendo Online. I could see a "hunting action"-like spin-off that takes elements from Salmon Run do pretty well though.
Nintendo as a whole has recognized the importance of new IP and revitalizing old IP with new ideas and they will continue pushing for that.
Splatoon is an interesting case because it's an example of a game performing disproportionally better in Japan than the rest of the world. They will definitely ride it out with Splatfests and special promotions for as long as they can but the franchise can go so many directions after that. I don't know if it makes sense for them to make a Splatoon 3 that would inevitably split the fanbase, something they probably want to avoid after introducing Nintendo Online. I could see a "hunting action"-like spin-off that takes elements from Salmon Run do pretty well though.