Again, forking is fine. Just do it with consensus -- or otherwise implement your fork as a stated altcoin. There are two camps here: one camp that either doesn't understand or doesn't care whether bitcoin is broken into multiple ledgers forever based on differing rule sets, and another camp that wants to avoid that. The block size debate is not worth breaking consensus over.
This is exactly what I've been trying to tell Fatty. He's just very set in his ways.

When the time comes, and you're on the wrong side of the 75%, then you're the one who's standing in the way of consensus.
So, don't be bad. Bad is not good.
And when you're on the wrong side of the 75%... rabble rabble rabble!
Two can play at that game.

In all seriousness, as I've said, a majority of hashpower is only good enough to trigger the fork. You can assume that everyone will immediately update to Classic nodes and therefore that only one chain will survive. But that's unlikely. I sure won't be updating. Let's see how it pans out.