Which future sets that you have already seen as a preview, do you find the most exciting?
For me, sorted by manufacturers:
Strelets: Napoleonic Guard chasseurs, Russian Infantry and Crimean French Cavalry- I can't wait to get them.
Caesar: Orc Warriors - they will lead the Immortals into battle
Forces of Valor: WW2 cossacks. Actually I'm hoping for some similar sets from Strelets, like: Cossacks Winter/Summer and Cossacks dismounted Winter/Summer, so at least 4 full sets.
Hat: Elephants, late Roman and El Cid Line, Prussian Hussars, French Chasseurs, German WW2 gun sets, 17th lancers and British Camel corps. Zulus if they're big enough- unlike their brothers from Esci and ACTA
Orion: Turkish cavalry
Pegasus: Gladiators, Polish Cavalry, farm houses
Redbox: I'm not sure that I can be excited, given the HIGH quality of their last sets - not.
Valdemar: Peasants on the march. If the scans show the final color I can use them for the Kingdom of Antioch, to support my Strelets' Normans and their allied mercenary Vikings and Anglo-Saxons against a force made up from Hat's El Cid range.
Coates & Shine, MIR and Valiant: don't offer anything that could possibly interest me
I had every intention of doing a list like yours so I went to PSR and looked at the future releases- then I lost enthusiasm when I found I wanted no less than eight different sets from Caesar alone (and at least two of each) and I hadn't even got to HaT. So I did a quick count and got 37 sets that I want.
P.S. I loathe the Napoleonic period so that does serious damage to the list of upcoming sets.