Doable but people will then quickly flee from the pools.
This is what I would have assumed but what I don't know (maybe somebody could enlighten me here?) is what percentage of the big pools mining activity are carried out by their own proprietary hardware?
BTC Guild (one of the big pools) currently have 22411 independent miners utilizing one server cluster, and 7428 mining the other. The amount of hardware 'owned by the pool operator' being utilized for mining, would be little to none.
Here are the stats:
https://www.btcguild.com/index.php?page=pool_statsPools are in the business of providing a service, not mining themselves. It would not be a pool if they owned all the hardware and were solo mining.
I may be missing something. You are saying miners mine independently although they share server clusters. Granted.
But if owning a combined mining pool which gives you 51% of the mining power does not allow you to launch a 51% attack, then why the recent hyper discussion about Ghash.io?