If you look at it from the perspective of “when will I be able to support 99% of users”, it will absolutely take a few years, but from the perspective of “when will a WebGPU game have distribution to more people than a Steam game”, it could be a lot sooner. Gamers generally aren't the same people stuck on enterprise-pinned old browser versions, so once Chrome + Firefox have support the chances of someone in the target audience for a 3D game having a WebGPU-supporting browser on their system are pretty high.

(I’m assuming you’re talking about distribution rather than tooling, but I acknowledge the tooling will take a few years to catch up.)