PoW in 2025–2026: Is the core model basically “done”, or is there still meaningful architectural evolution left?

I've been following Bitcoin mining and PoW for quite a while now, and one thing that always strikes me is how remarkably stable the core design has remained.

SHA-256, difficulty adjustment every 2016 blocks, 4-year halving schedule — basically all the fundamental pieces Satoshi put in place in 2008/2009 are still working exactly as originally specified.

At the same time the actual industrial reality has changed beyond recognition: we're talking millions of ASICs consuming terawatts of power at global scale, something no one in 2009 could have realistically pictured.

So I've been wondering lately:

Does Proof-of-Work as a consensus mechanism still have meaningful architectural headroom left to evolve — **not** by changing Bitcoin itself, but as a general model?

In other words: is it conceivable that in the future the hardware / energy we dedicate to securing a PoW chain could be doing some other simultaneously useful computation besides "just" finding valid SHA-256 hashes?

I've seen a few research efforts and alternative chains experimenting with exactly this idea (useful-work PoW, proof-of-useful-work, etc.) — basically trying to make the energy expenditure produce something society/values outside of network security.

Curious what the more experienced people here think long-term:

Do you feel the current PoW model is basically in its "final" mature form and will mostly just get more efficient / cheaper / denser over time?

Or do you think there's still real room for non-trivial architectural innovation in how we structure distributed proof-of-work, even if Bitcoin itself never adopts it?

Thanks for any thoughtful takes.