However, this raises some endgame concerns. If mining ever becomes *too* unprofitable, because, say, transaction fees can't cover electricity costs even of those nice cool 28m chips, the pressure will build to add some inflation into bitcoin's protocol. As technologies ramp up, there will be fewer and fewer entities profitably mining. This is the consolidation people are concerned about.
Such a scenario is virtually guaranteed at 21mil coins.
Miners will have to struggle to remain profitable as things settle down, and this will require them to be creative with waste heat, putting it to good use. But this environment will favour smaller, more versatile miners. It's a situation of "diminishing returns to scale".
And yes, a majority of miners will have to agree to, download, and install a new protocol, so it's somewhat democratic.
It takes a lot more than a majority of miners to agree to change the inflation schedule. Any full node who doesn't agree to the change will end up on a different chain. SPV nodes would currently follow the miners like sheep, but there are known upgrades to the system that would prevent this.