That's actually not correct. Whether 2012 or 2015 is chosen, a date certain will soon be a Rule (note the capital R). Once the Rule is in place, it has the weight of law. For that to change would require:
1. A new Rulemaking procedure, which requires a new NRPM, Comment Period, etc.
2. Congressional intervention.
While I can't speak for Congress, administrative agencies rarely go through this process twice. It undermines predictability in the law, which is something all legislative and quasi-legislative bodies should consider, and frankly, such agencies can be a bit lazy. Again, the rules are what the rules are; once in place, they should be left alone.
Yes, the comments may be interesting. One never knows what they will say. But, the Commission is really only required to "consider" them, which basically means they must read them. That's all.
Still, now that you understand that the Sun is setting on these back-door radio stations, you can file a Comment. It's not just for lawyers, even laymen can. I have filed several. Here's one, to show you what they look like:
http://ecfsdocs.fcc.gov/filings/2004/04/06/5511238364.html
Have fun with it. Cheers.
DE