Trust me, I 'want' this to happen.
But it doesn't seem like something Sakurai would do. The fact we still get staggered releases makes it seems like he loves dragging this out.
i agree that sakurai is the final arbiter on marketing decisions, but at the same time, this
is a namco fighting game, just like tekken. the move towards a season pass already suggests they're moving closer to 'standard' fighting game protocol, and if namco told sakurai from experience of tekken's second season pass that clarity of content generates better sales, he'd probably defer to said experience.
again, it's all hypotheticals; certainly, a reveal all at once like that would be odd for smash (then again, we had everyone is here). however, based on the general trends of season pass reveals nowadays, as well as shareholder demand to see more immediate profit from the pass (instead of people holding off because of uncertainty), i don't think it can be dismissed out of hand.