If the price for games went to £70 per title I couldnt justify spending that amount on something that would be played for 6 - 9 hours.
The pre owned market would go through the roof with demand higher than the supply!!
Most games in the future will be heavily supported by DLC, You spend £40 to £50 (eg COD 6) buying the disc, and instead of getting the next release on disc, you download a new single player campaign every 9 months costing £25 - £30 with multiplayer maps being released as and when. Then further down the line, games will be download only for the next gen consoles, this should automatically reduce £7 - £8 per title for the developers.
I wouldnt pay more than £35 for a title that was download only,