This will almost certainly happen if these subscription-type services become popular. Which means fewer people will be buying AAA games on Day 1, more studios will shutdown etc.
Why?
There are a few things at play here:
1) If 10 million people are subscribing to the service that is a lot of revenue on an annual basis.
2) Most gamers are not going to wait to get the game as part of the service if it is a game that they just absolutely must have. Online play, new rosters for the football season, big time BF players. They will need to have a game day 1.
3) Nothing says all games come at the 12 month mark. Could very well be a case that some titles don't get on for 2 or 3 years. Might devalue this service some, but I could see a really long RPG like Dragons Age taking 2 years go hit the service.
4) DLC purchases will still take place within a lot of these games. Perhaps more DLC than would have ever been thought possible since people see the game as "free" and they are only buying a map pack for it.
5) That 5 day early preview with 10% off the digital price is not by accident. That is designed to get you hooked on a game. Get you a save-file built up and then dangle a higher-margin than retail carrot in your face to jump in then.
Ultimitely there is a chance that some games will suffer because of the service. Its the one downside for EA if it could wind up eating into day 1 sales. If that happens, expect the service to shut down.
They will very easily be able to see if the people subscribing the service are or aren't buying games. But don't think that everyone will go headlong to their doom. If this service hurts the bottom line they'll end it.