I'm not an expert, but if 51% of the existing hashpower doesn't want a change, it sounds less a 51% attack and more like miners voting against something that isn't in their interest. The whole point of blockchains is that the incentives are supposed to be aligned between miners and users. If that isn't the case here, it sounds like a problem.
You should think of miners as bodyguards. They aren't intended to be active participants on the network, they are intended to provide the service of securing the network and serving the interests of the users of the network. If a group of bodyguards at a concert vote democratically and 51% of them decide the singer shouldn't be allowed to go on stage and sing (because of a grudge or whatever), is that a problem? Yes…
These people are spending millions of dollars in electricity keeping things ticking away. If they stop, Ethereum's vested interest drops significantly. Since it is a fiat currency, less participants make it, unfortunately, less valuable.
Telling 60% of holders their currency (or income toward driving that currency) is not how you keep them on your side, just like old mining town scrip is only worthwhile if the mine works. The second the mine shuts down on a union strike, the scrip becomes paper.
On a personal note, I hope the miners get their due, because it was the initial philosophy of Ethereum. If they don't, I am curious to see how Ethereum moves w/r/t proof of stake vs proof of work guarantees. PoS seems at odds with the initial platform, and possibly long-term problematic for their "contracts-first" architecture.