Any fork with a low hashrate would be subject to what Luke-jr did with to Coiledcoin.
Hi Richy, what if the lesser fork adopts a new proof of work algorithm that obsoletes the existing mining hardware?
I believe when Luke-jr did what he did, we were not on ASICs yet. Starting from scratch is rolling the dice. There are a lot of powered down (or being used on altcoins) GPUs out there. Who controls them?
ASICs will be produced for the new POW in a couple of weeks to months tops in any case. Or would be if it wasn't going to be effectively dead.