4k\5k Shooting, editing etc has been around for a few years already. Red were shipping them 5 years ago? Admittedly a lot went to indy or boutique producers but they have been used by studios. Whilst 4k cameras do increase storage requirements etc but HD has been around a long time and computers have been improving. It's fair to say 4k will cost more than 2k does now, but its also valid to compare 4k costs now to 2k costs when HD entered the mainstream market nearly 10 years ago.
There will always been some whining when costs go up, but it's not like studios won't recoup it. In another 2-4 years 4k screens will likely be down to top end consumer pricing (maybe $5k ish range), bluray will have 200gb+ discs for storing the content. No doubt they will add 10 bucks onto the cost of the discs to recoup this, but part of me thinks the additional cost of 4k will be dwarfed by the cost of the riders for any a list celeb.