I have a lot of disagreements with the decisions made in Smash 4 that goes beyond character inclusions and cuts, more so than I've had with any past installment, which seems very odd to me as I've usually never had any major disagreements with my otherwise favorite video game developer. It's still the best installment in the franchise, but not because of the new things, but because of how it builded on past things. Because of this I've come to question Sakurai's future with Smash, so despite how much I love him as a director, with both Kirby and Smash in my top 3 video game franchises (only behind Metroid), I think that at this point the franchise will need a new fresh outlook if it wants to move in the right direction. On top of that I also think it's about time for Sakurai to move on, the job as a video game director is stressful enough on its own, but Sakurai has always stepped it up a notch, he's always hands-on and decides every little thing, and to do that 3 times (taking into consideration that 64 was developed much more casually) with a franchise that's so packed with content is going to leave scars and could end up forcing him into retirement much earlier than he otherwise should, which would quite frankly be nothing short of horrible. I honestly think it was probably too much for him already to take on developing these two games with his injury, I think he's being a bit too careless on the consequences it can have. I'd like for Sakurai to take a long break, let it be 5, 7 or even 10 years if that's required, and once he's ready to come back to developing I'd honestly rather see him begin innovating again rather than go through the same old process with Smash. Sakurai has a very unique way of thinking and it leads to very unique games, but since Brawl the only thing he has developed has been Kid Icarus: Uprising, Smash seems to always take top priority, so I'd be very interested in seeing just how much creativity he could chunk out without having the huge weight of Smash on his shoulders all the time.
As for the next installment itself, I foresee that it will feel a lot more like a copy/paste than even this game did from Brawl, with or without Sakurai. The workload and expectations increase drastically with each installment, come next installment people will expect a character roster of probably close to 60 characters, at some point they'll need to either cut a lot of characters or simply just copy over the veterans with minimal to no changes at all. One thing's for certain, the next director, whoever it may be, will have one hell of a job to fulfill. I personally wouldn't want to be the one to take over that job, jumping into a franchise like this and having to take it to the next level immediately sounds impossible to me, but at the same time it'll have to happen eventually.