A Deluxe in 4-5 years will be the best case scenario. Add Crash Bandicoot, Dante, Geno, Dixie Kong, Bandana Dee, Doomguy, Ring Fit Adventurer, Twintelle and some Pokemon and we'll have the most definitive roster ever.
But as of now, I really can't complain. I remember being disappointed in Kazuya back in E3 because I was expecting Crash with the rumours and all, but now that I own the character I really like it, I have played almost all Tekken games and I have a history with them, but in that period I was so focused with Crash and that announcement did not much to me.
After that we had rumors of Sora in Smash. Now yeah, I admit it, Sora was always my first choice, but I always thought it was impossible, and in my mind Sephiroth announcement erased all the possibilities, but here we are.
That said I really hope Crash makes it, in some way, with THIS roster. I don't see Nintendo releasing a new smash without some heavy hitters from Ultimate, we know how some (toxic) fans are and Twitter is a big site where they can express their toxic behaviors. Best case scenario is this Deluxe theory, but in 5 or more years I think.