Miners can't fork without the userbase also doing so--not meaningfully, anyhow. There seems to be a misconception that miners are able to, "rewrite", the network rules if enough of them collude, and this simply isn't true. By the logic that miners could force the 2MB block hardfork, they could also decide that the Bitcoin reward per block should increase to 100, because they have majority hashpower and anything they say goes, right?

That's not how it works though. What happens if miners decide to switch to some rules that defy existing consensus rules is that all other nodes--users, merchants, exchanges, other miners--will see their blocks as invalid and reject them, and miners and nodes using the existing consensus rules will continue to build and validate their own valid chain. The forked miners will effectively be mining their own fork that no one else is using, wasting their own hashpower for a no-prize.

Something they could do with majority hashpower is harass the network by building malicious (but valid) blocks--perhaps by not including any transactions at all as a sort of protest. They'd have to be pretty nuts to want to pull shit like this though, as their profits come directly from the value of the Bitcoin they mine.