What is the hypothetical roster size for you?
But popularity does not matter here, only franchises with relevancy. The other question is why does Rosalina get cut but Waluigi gets added? What does Peach and Bowser add to the roster that Mario doesnt fulfill already?
Ike is the symbolism of when Fire Emblem itself start failing as a Franchise. Path of Radiance and Radiant Dawn marked when the series started stagnating in sales. Or does that not apply here?
What exactly do you mean by "rebuilding the franchise" and what is the roster cap size?
So if what I am understanding is correct, this would be the final roster:
Heh, I'm talking about the series likely going into a reboot and the roster getting a cleansing and down sizing. I can't give a definite answer as it depends on how bold they start out with. But quite a few people were even questioning whether this game (before Everyone is Here) would do some massive cuts due to the roster size. Now we're at what appears to advertised as the peak of Smash Bros, so a down scaling feels very possible afterwards.
With this mindset, it made me start doubting many options as they may not hold up in the long run and end up just hurting feelings in the end. Ridley, King K Rool, and Isabelle were all very popular adds that are coming from series that are still healthy and thriving. I'm not sure if Sakurai will touch Sin & Punishment as an example no matter how much he teased Saki could make an amazing fighter simply cause a down sizing would likely boot him out.
3rd parties are even riskier to predict as you have both Nintendo's and the 3rd party's input as well. Microsoft would be more likely to crave Mindcraft getting more spotlight to sell more, but Sakurai may want Banjo for the fans wanting him. And with reducing the roster, it also depends on how much they want to go forward as a Nintendo fighting game or if they want to broaden it even more to a crossover game.
To put it out there in theory, the Mario cast would be first reduced by
with the core four remaining in terms of verterans.
Nobody compares to their level of iconic power for Nintendo.
And then depending on how much space allows and what new IPs or existing IPs grow, the Super Mario series would probably be a front runner for a newcomer. Toad is one of Nintendo's biggest icons and a reworked Peach may not need him. Waluigi has huge popularity with casuals... so they may throw the fans him instead. If it was a fair world, Toad would get in first. But it isn't.
The final roster you posted is purely throwing words in my mouth. I'd rather not sit and go through the roster full tilt right now and deduce the full reboot roster. It'd be far off anyways, but my biggest wonder is how much it will effect who and which newcomers we get now. Does he risk adding Captain Toad who may fade away soon/go back to normal Toad or why add Krystal when the series is flopping and may be dead by the time Smash 6 would be made resulting in the series not really qualifying for 4 characters? Meanwhile Metroid/Ridley and DK/King K Rool and AC/Isabelle are safe bets to still be floating down the road. Well King K Rool may not be himself, but the DK series will likely still be alive and well.
I feel Isaac would need the additional push of being revived to help him out. And it's quite possible he may get the Pit treatment (hopefully better) and become a hard hitter. But at the moment, I'm starting to ponder if he's avoiding any off the grid picks this time around as we haven't seen any retros or console reps like Duck Hunt or Wii Fit.