What are the chances we could potentially get Goku in Multiversus?
It's far more likely than Smash that's for certain.
I honestly wouldn't write off anime characters, but I don't necessarily think some of the more popular characters people have suggested would be as likely as people think (given the amount of money that'd probably be in licensing, and maybe some of the difficulty behind that.) That said, I do still think they'd be cool.
Random side note but I feel like one of the more underdiscussed "likely" candidates in this role would probably be Haruko Haruhara from
FLCL - it's not a big enough franchise to cost a fortune in licensing, but
FLCL was a pretty big part of [adult swim] and Toonami history to the point that [as] was the premiere of
Progressive and outright ordered
Grunge and
Shoegaze, plus Haruko fighting with a guitar containing a pullstring that activates a chainsaw or a rocket launcher that she can also use as a hoverboard while driving a Vespa that can travel at the speed of light through deep space would be a pretty fun moveset