I think it's widely accepted and established that Abrams wants to use more live actors/costumes/models etc. as opposd to digital effects.
If stormtroopers do indeed feature, I imagine we should prepare ourselves for two realistic eventualities ...
1. Exploitation of the stock of intact "tour suits" (or even reproduction base don tour suits), i.e. lots of ROTJ-style TKs
2. A batch of new stormtrooper costumes created from scratch
Let's be honest here, we're a sensitive bunch and, when it comes to TKs we find it hard to approach anything with a truly open mind, this could be great or, depending on your relative sensitivity or puristic nature, could get pretty traumatic for some.