It's already happened: a Steam game bundle where almost all of the games are available for Linux:
Buy Tripwire Interactive Bundle
You get the following Linux games:
- Red Orchestra: Ostfront 41-45
- Killing Floor and all DLC
The only non-Linux games are Red Orchestra 2 and The Ball.
EDIT: I have since learned that this bundle has been available for years (before the games had Linux ports), and that it has gone on sale for half price from time to time.