Yes, other way to put it is that the incentives for the software are designed in a way which makes certain changes extremely unlikely. However some changes are happening all the time (features added via a soft fork)
A huge chunk of the miners fought tooth-and-nail to not increase the maximum block size. The chance of them agreeing to something like this seems very low indeed.
Doesn't actually need the miner's consent, only needs the market to agree. Problem is there isn't really any entity with sufficient authority for the market to follow, so it will tent to bias towards the status quo, and miners tend to have a lot of money and so influence in the market (both hard and soft).