I don't think that mining necessarily will create a "problem".
What will create a problem is if the energy is not sustainably sourced, and I think that is totally out of the control of bitcoin miners.
i wouldn't say that. this all boils down to profit motive. if the mining profit motive drives unsustainable energy use (like coal fired generation), that is not "out of the control of bitcoin miners". the bitcoin miners don't give a shit about sustainable energy. they only care about profit. that's the fundamental problem that we as society need to fix.
this is why sensible power plant operators (who need to balance their grid loads) and governments who are serious about sustainable energy need to incentivize bitcoin miners to make the right decision. we need to drive bitcoin miners where there is excess electricity supply. hydro power during rainy season that
must be consumed and other things like that.
if you just leave bitcoin miners up to their own devices, they will just opt for the cheapest energy. if that's fossil fuel, of course they'll use it.
Furthermore, IIRC a lot of bitcoin mining really just uses up excess electricity that would otherwise have went down the drain anyways.
that's the ideal but i'm really not sure that's what is actually happening. very few policy makers have actually created economic incentives for this activity.