I wouldn't be surprised to see a Tapco or Promag type manufacturer try to market some polymer ones.
But really, the standard aluminum mags hold up great (much more durable than M16 aluminum Stanag mags), weigh about the same as what polymer would, and are ultimately going to be more durable than polymer (both to drop fracture and wear over time). I just don't see the need.
The AIM mags are for all intents new. I don't know for certain, but I'd imagine eventually we'll be seeing new, current production not new old stock, mil-spec aluminum mags out of Eastern Europe but to match the quality they'd be more like $30-40ish, not the $15 we're seeing the surplus stock at.