I think its interesting that mainstream PC gaming press is now talking about Linux. We have the benchmark Youtube channels doing some benchmarks of it as well and plenty of reports of "it just works", which is pretty promising at least for the games that aren't intentionally excluded by DRM. For me its still controllers and equipment incompatibility due to my VR headset and sim wheel/pedals setup, I use Linux everywh…
The last remaining roadblock is kernel level anti-cheat frameworks. Pretty horrible technology, and unfortunately a good majority of the gaming industry by revenue relies on it.
The best Valve could do is offer a special locked down kernel with perhaps some anticheat capabilities and lock down the hardware with attestation. If they offer the sources and do verified builds it might even be accepted by some.
Doubt it would be popular or even successful on non-Valve machines. But I'm not an online gamer and couldn't care less about anticheats.