You could probably already make something compelling like a small myst-style game that uses largely static assets with existing tools, taking advantage of being able to render real world environments with high fidelity.

However for more typical games there's still a long way to go. Most of the research focus has been towards applications where existing mesh-based approaches fall short (eg. photogrammetry), but this isn't really the case for modern game development. The existing rendering approaches and hardware have largely been built FOR games and leveraged elsewhere.

Rebuilding the rendering stack around an entirely new technology is a tall order that will take a long time to pay off. That being said, the technology is promising in a number of ways. You even have games like Dreams (2020), which was built using custom splat rendering to great effect (https://www.youtube.com/watch?v=u9KNtnCZDMI).

It will require major changes to the art pipeline. New tools and tech that hasn't existed before. But, that tech is being made right now at a surprisingly fast rate. In a couple years at most it will be possible to make at least an indie-level game with splats. Maybe even with models, animations, audio made to the 80% level with generative AI.

I've only seen it used for static environments/objects but no animation/dynamic objects

I could imagine a hybrid approach of doing the environment with this but other things rasterized as normal and comp'd on top

The big problem though is that the workflow/format is completely different from how current 3D games work so you'd need a lot of custom engine work

I think we'll see some experimental games in the next few years

I don't see how things like real time lighting will be solved by this. That is one of the most important aspects of 3D rendering.