I have no idea how RTX actually works, but based on the fact that exploits the existing rasterization architecture, I assume it adds at least one (very fast) pass.
Yes, that seems likely. But can you use it to drop some of the others?
Probably, yes. The only issue I see with that is the fact that Raytracing is only supplementing current rendering methods, not replacing them yet. The performance is not there yet. In a few generations we might see fully raytraced games, but not for a little while I would guess.