Given the first two of those kits aren't plastic, the description to me sounds more like say, Assault Marines and Devastators, the molds for which are getting pretty worn out in the same way Tactical Marines were. I'd be doubtful of getting a new plastic commander too, given the trend for characters has been clamshells, but it's possible. It'd definitely be a treasure trove of fancy bits if it happens. It'd have to be, the current multi-part Commander, and command squad for that matter, look positively plain compared to the new Sternguard box.