I'm hoping its an update to the end dimension and overhaul so many cool features
But considering that mojang has made so many MASSIVE updates in recent years (1.13, 1.14, 1.16, and 1.17) I believe that 1.19 could be more of a smaller update centered around a few new features, sort of like 1.15 with the new bees and major bugs that had been fixed.
Who knows? Maybe the end update could come in minecraft 2.0. It makes the most sense tbh.