Possibly. But who cares in the short term? 600 will get you platinum status which means free rewards come summer time
Also, to my knowledge they don't expire (though reward items may go away, I guess), and even if they do, it's probably a long time from now (the surveys are up for like 3 years or some shit just waiting on you to do them).
"After Play" surveys come up after you register some of those games. Also, if you have games that don't give coins for registering, you might still get coins from doing a survey about said games. So who knows? A lot of the coins I got this time around came from a backlog of surveys I had left over from last time.
