You won't see comeback for steel rims for a number of reasons. The first is purely practical. The equipment for making these has been mothballed, and production capacity is now devoted to rims made of extruded aluminum. It would take a serious benefit to overcome this momentum. There's also the issue of plating, which for environmental reasons is out of favor and avoid when possible. Stainless steel is too expensive and hard to work with to make sense.

Then there's the bicycle needs. The ability to easily extrude sound structural shapes, form them into rims, join and/or machine the sides makes aluminum the winner here. Excellent strength to weight ratios and workability will keep the world on aluminum for anything but low end utility bikes for years to come.

If anything, more disc brakes opens up opportunities for rims made of engineering plastics, which could offer all the benefits of aluminum at a lower weight with the added benefit of resilience and shape memory that aluminum lacks.