I don’t think they would try to kill java edition. It’s not like the past decade of mods are going anywhere, and java players aren’t exactly known for being afraid to play on older versions. The most popular modpack is for 1.12.2. Hell, I recently found out most modern features have been back-ported via mods to at least 1.7.10 with older version inspired retextures and all. I don’t see why that wouldn’t continue to happen, even if Microsoft stopped officially updating this version of the game.

And I doubt most of the people still playing on Java have any interest whatsoever in the bedrock marketplace. So they’d lose all of their goodwill with a massive chunk of the community, and for what?