The problem in this scenario will be feature disparity. If they want, they can add cool stuff to Bedrock, and make vanilla Java version feel old and obsolete just the way 1.12 (which probably has the most mods) looks now when compared with fresh 1.18.

Then, by making Bedrock available to people who paid for Java, they would give a hassle-free way for players and modders to try it, and many will probably stick to the latest version.

I do hope, if this scenario comes about, the community will keep the Java version alive by maintaining feature parity, but there’re fundamental issues where some features might not be easily backported on Java due to performance limitations, plus community fragmentation as different modders try to backport same new features in different mutually incompatible ways.