I get the impression that every time a consensus rule change is suggested then people assume that the miners/mining pools have the last word if this rule accepted or not. But isn't it up to the buyers?
Take the blocksize limit for example: A lot has been talked about which pool would go for which approach regarding the blocksize. Now let's assume one part of the miners would got for approach "big blocks" and the other would go for "small blocks". This would result in a fork of the blockchain: Bitcoin would essentially be split into two currencies: BigBlockBitcoin and SmallBlockBitcoin.
If I where to buy some Bitcoins after such an event, then I'd expect Bitcoin exchanges to offer me these two coin types. I would be able to buy the coins mined under the rules I like, it would not matter if they where mined by 90% of the miners world-wide, or by 10%.
Eventually one approach would lose traction and the coins value. So isn't it ultimately up to the buyers to decide if a coin is successful or not?