Metropolis has lots of advantages, but it has serious problems for realtime or animated applications, in that it tends to flicker or have noticeable low-frequency noise. This is less of a problem for stills.

RTX can absolutely accelerate path tracers, even for non-realtime applications. The underlying framework is definitely flexible enough to support a variety of rendering algorithms, it's basically accelerated BVH and intersection, with shaders to control behavior.

The biggest advancement I've seen lately is advances in denoising - the ML-based denoisers are incredible, but others are also impressive.