This is so stupid. It is possible (but certainly not assured) that a coalition of Coinbase and some other big exchanges could apply enough economic pressure to force through a hardfork vis-à-vis the economic majority, but:

- If they fail, it will massively damage them.
- If they succeed, it will massively damage Bitcoin. A large percentage of users will refuse to switch, so they've automatically reduced the size of the Bitcoin economy -- both the price and their number of customers will go down. And BIP 101 itself is basically suicidal.

It looks like BitStamp is one of the most sane exchanges nowadays.

P.S. I was trying to find that quote from Gavin where he describes his vision of Bitcoin's future as being one where full nodes are only run by what are essentially banks. It was several paragraphs long. Does anyone have that?