I imagine it might become an issue with games that use HD graphics, especially lots of FMV like many Japanese games. The Wii shouldn't have any trouble, seeing how a game as large as Twilight Princess fit on a Gamecube disc, and the 360 seems to be well off with games like Mass Effect, Halo 3 and Gears fitting on just one "last-gen" disc.
Of course if a competent developer starts working with a BR disc, and has a minimum of 50GB to work with, they'll definitely be able to pull off some features they couldn't do before. Equally sure is they'd have serious trouble ever slimming the game down to standard DVD size, which is why I expect to see quite a few game that 360-owners would like stay as de facto exclusive.
Still, it looks to me like the cost of developing jaw-dropping HD visuals is doing much more to prohibit the length of games than disc space ever will.







