This is about as stupid as the situation where everybody was panicking about ASICs and I'm seeing the same level of panic too, the difficulty is designed to take care of this problem and makes it distinctly unprofitable to throw lots of hashpower at Bitcoin. ASIC's were released and it wasn't a disaster, somebody has control over the a huge amount of the network? It will start becoming unprofitable just as ASIC's and people who try this will be forced to shut down so they can stay in profit and lower the difficulty.
You could easily argue that it already has been a disaster, it just hasn't reached it's full potential yet. Cex.io controls as much of the mining power as they do mainly because ASICs are available and the barrier of entry to mining has become much higher. Judging from their press release it will only get worse.