I think people are underdestimenting Crash's chances of being in the base game. Sure, he can be DLC and I'll happily accept that, but some are saying that because of N. Sane Trilogy being a 2017 title (2018 now on Switch) and the roster for the next Smash being decided in mid/late 2016. But see, the thing is that N. Sane Trilogy was announced in 2016 and all the coy play of Activision regarding the PS4 exclusivity since the annnouncement, made it clear the game was planned to be later in other systems since the beggining.
Additionally, of course, we have Skylanders Imaginators which was released that same year and in multiple systems.. Wii U included (where you had our first crossover between Crash characters and Mario/DK characters).
Nintendo was closer to Activision at the time yes, mainly because of Skylanders and probably they were aware of Crash imminent return (and they should, since their characters was about to have a crossover with him) and that also resulted in Imaginators being a launch title for Switch (and with the feature of keep all your Skylanders after just one scan, which pretty much means its somekind of definitive edition).
Of course, the significance of N. Sane Trilogy on Switch is absurdly bigger than any Skylanders game, but what I'm saying there's reasons to believe that Nintendo was at least aware of all this situation of Crash revival while the Smash roster was being decided. We also have to count the Ballot, were he probably was decently requested.
but wathever is the case, I think he has a great shot of being in the game this time and proably the guest character that would generate more good marketing for the game.