After thinking about it, I think the Whole "Brings new Mechanics to Smash" for FP2 is more important than we might realize
I Think there's less Chances of us Seeing more Simple characters in FP2, because if they can't add some of these characters now, it would be hard to add them later in Base roster of Next Game
Pretty much if you compare the Base roster Newcomers of this game, and the ones of FP1 and what we know of FP2, you see that the base Roster Newcomers are more Standard in Comparison to the DLC. I think they go with more Standard Characters because It's easier to balance out the Newcomers to the Rest of the cast, and it's easier to just make the character in general. when you're trying to bring back every veteran, Balance them out and such, and make a Whole Game along with that, Adding some of the Complex Mechanics we've seen with the FP1 Characters could be too much. Even if not Complex Mechanics, they still have Alot of modeling that usually tops the ones in base game (Joker needed Arsene Model to be made... or at least made to sync with Joker. )
DLC is the Perfect Avenue to bring in these Complex Characters now. So I actually do think that while the Characters have to be reasonable to develop on Schedule, they also do have to bring new ideas, that might not be realized when pressured to bring a Whole new Game with it
So I think Characters like Crash, Bandana Dee, Waluigi (if they aren't going to do something Very Outlandish with him), and more might be less likely because of this. They still have good chances to come to FP2, but I'm just saying, they could be Saved for Smash 6, where they'd be Newcomers people would want to see, but also be easy enough to develop while trying to make a Whole new Game
I Know Sakurai said he's focused on Finishing the DLC, and isn't thinking about Next Smash, but I think the comment about him coming back if Nintendo ask him for another might say deep down, he is thinking about what's to come next.