How so?
Crysis 3 is around 15gb isn't it?
Just because blurays can have 50 or so GB of data doesn't mean games are going to be anywhere near as big.
Games are going to take advantage of the increased format size. I obviously don't expect all to be 50GB but I do expect quite a few to have above the 20GB range going to 40GB.
However let's go with Crysis 3 being the minimum so assuming a 500 GB, then you get 33.333 games out of a HDD before you have to buy a new one. That isn't including DLC and patches.
Now let's assume the average size of a next gen game is 25GB then you get 20 games before DLC and patches.
There's absolutely no reason why you'd have to have every single game installed to the HDD at once.
If they're making the disk useless after the initial installation then yes there is a problem. I can't repeatedly install it.