I believe existing responses mostly capture my feeling here so I'll keep it brief.
I agree with @Karl here that the fundamental issue is existentials receiving the "blessed" bare-name syntax. If we think that the language should guide users towards generics first (or at least put generics on equal footing with existentials), then IMO that's an argument that elevates the bare-name existential syntax to the level of "active harm" that would begin to justify what would presumably be a massive source break.
This would be a harder bar to clear, obviously, but IMO we should explore this direction first and only then consider alternatives if it's decided that the break would be too burdensome for developers.