Will they go under? Can they survive on half the amount of income?
I think they can survive on half the income, the price remained around 200-220 for a lot of time last year, they did survived that and technically it will be just like that if price doesn't goes up.
25*220=5500
12*420=5040
Not that big difference, though the price should go up but if they decide to stop their operations, their place will be taken by others.
It is not easier for other to take place of them as it need lots of investment to run mining farm.
If majority of those chinese miners decide to hold and pump price a little bit than price will be moved almost doubled due to other trader's phycology and greed.