Myself, I have dreams, plans, figures on the shelf or actual painted units for:
Roanoke/Jamestown early exploration campaign
King Philips War
War of 1812
Patriot Hunters Raid
Plains Indian Wars
I've toyed with doing something with Korea but have no serious plans and likely won't have unless I find a sale on IMEX figures . . . I can never pass up a bargain.
Having been in the hobby for 40+ years I am not hesitant to make conversions to give me the figures I want. Being a painter I could not care less of the base plastic colour most of the time. Accordingly the dearth of new ACW figures doesn't bother me, I already have more than enough for my purposes, even if they are less than ideal. 1812 figures are easily converted from existing sources with little more than a clever paint job. My biggest problem is finding decent U.S. Cavalry for the plains wars. Most sets have them wielding sabres that were, in reality, left in storage and wearing kepis rather than broad-brimmed hats.
The other major difficulty is finding troops in full skirted frockcoats and tapered shakos suitable for Mexican regulars and Canadian militia in the 1840's and 1860's. The recent discover of the Waterloo 1815 Risorgimento Austrians (on sale) may have solved that problem for me . . . but they may end up getting used as Austrians because I'm also interested in the Risorgimento.