So, whatever this mysterious "Bad News" is, I don't think it's a specific character getting in: As much as I'm embittered by Steve, as much of a meme Jonesy is, and as much as KOS-MOS seems like an odd ending choice, the simple truth about Smash is that Everybody wants SOMEBODY in this game
The only truly controversial characters I see are Tracer, Sora, and FNAF. Tracer due to Blizzard's recent shenanigans, Sora because people hate Disney now, and FNAF because it's so far out there and people have been asking for Shovel Knight, Shantae, or Quote to be the Indie Rep. And even THEN, they are still genuine requests
I don't think anyone would truly be upset over Sakurai announcing his retirement, we all love and respect him too much
Nah, I think the bad news would be something like:
--The next wave of DLC is all first party, and Geno originated from a Mario game so by technicality he fits in. Which would mean the dreaded FE rep
--The next wave of DLC is the last we're getting, which means only a few coveted spots left
--Popular requests getting Mii Costume'd