I think it's probably time. There's no denying that Sakurai works extremely hard, and he's done some great things for Smash. That said, I think the transition from Brawl to 4 shows that there's not a lot left he can add to the series.
There's not much to add to the series except characters, stages, and mini-games. I think it is time to start fixing the solo modes and the record keeping.
Classic Wii U was awful, repetitive, and tedious. Classic 3DS is guilty too but at least it doesn't have 8-Player matches like Classic Wii U does... and it doesn't have Master Fortress. It's so stupid how we are limited to two stocks per match. I'd like to be able to select how many stocks I want per match. I wish they would stop making Classic Mode a boring chore and make it fun like they used to do in Melee.
Master Orders is lame, Crazy Orders is where it's at. They need to get rid of Master Orders and make Crazy Orders its own mode where players don't have to pay coins to play.
They also need to stop making difficult challenges. The challenges are getting more and more sadistic and frustrating in addition to being tedious and repetitive. Beat All-Star on Hard with all characters? Defeat 8 enemies in Cruel Smash? Screw that!
Smash Tour is the worst mode because it's so boring. They need to just take the final battles from Smash Tour and turn it into a new Vs. mode where players can select multiple characters as stocks. Smash Run is where it's at. It's the best since Melee's Adventure Mode.
I just want solo modes to be fun and not feel like a chore. I have more fun in Stadium mini-games than I do with Classic, All-Star, and Events.
I wish they would get rid of recordss and milestones. Why do we need to know all that? Why do I want to know the time and date I unlocked something? Why do I want to be constantly reminded of the order of trophies I obtained? Why do I want to be constantly reminded that I don't play certain characters as often as the characters I always pick? Why do I want to know how many times I turned on the game? It's all pointless waste of development time programming the game to keep track of literally almost everything when they could have used that development time to balance the characters and making sure the stage hazards aren't obtrusive.