50 minutes is quite a lot, even if Smash takes up half of it. There could potentially be new trailers for quite some stuff we're expecting; BotW2, MP4, Snap, Bayonetta. Though it does say "first half of 2021". Obviously there'll also be a sizzle reel of small stuff that takes up 10 minutes. I hope there's also a surprise at the end, even if it'll be something I wouldn't be buying, but just because it's fun.
It is the 35th anniversary of Zelda this year, so Im sure we get something from that series.