If that happens, bitcoin fails!
Yes, I think that way, too.
Wondering saving bitcoin is feasible or not.
But I also think that at the stage of extreme concentration, we may have to embrace it.
And Bitcoin will be like just one of the money services operated by ordinary corporations (still all transactions might be visible to anyone, though).
It's a little more complicated than that, the consensus of the network doesn't rests only on hashrate power, ever full node is a vote, so it may be impossible to control the protocol like that.
Plus it's a free market, every bitcoin user can fund mining companies through Bitfunder, BTCTC, etc, and buying mining rigs, it's a profitable business so, probably, for the near future we're going to see mining companies popping up all around the world, and the concentration of hashing power will vary a lot, like it did in the last 12 months.