We cant have centralized mining.. its something i dont like about Bitcoin, mining tends to be centralized. It would only take a small missile to ruin a big mining facility and bitcoin would collapse.
Ideally we want it dispersed not all in the same place
Well if that did happen and mining was mostly centralized it would re-adapt to decentralized with a lower difficulty.
Even if it is mostly "centralized" - there is more incentive to be an honest player as well. Mining farms were predicted from the beginning - as well as nodes residing in these farms.