Well, next up are Russian and Prussian dragoons. Judging by the slow speed that Renedra turn stuff around, only big-selling plastics will appear, indeed, I note that the forthcoming plastic Prussian reserves seem to have vanished from the Perry site! 
I would not over-interpret that. The twins occasionally re-shuffle the items featured on their workbench section : it doesn't mean the Prussian reservists have been postponed or put on the back burner, just that Alan and Michael had newer stuff they wanted to show.
I suspect that in the weeks to come the twins will post some info as to which plastic set(s) will be next. Besides the Austrian Napoleonics and Prussian reservists, we also have in the queue Russian Napoleonic grenadiers (including heads for the Pavlov regiment), ACW Confederate infantry (with a companion Union set in the works as well, I suspect, though this has yet to be confirmed), AWI British and Continental infantry with some militia to follow, and the two WW2 Deserts sets previewed at Salute - enough to keep Renedra busy for the next 18 months at least, I'd say.