The Scene: You check mmochamp, twitter, your google feed or wherever the heck you get this kind of news from, and there it is. WarCraft 4, a bright shiny new logo. It's legit, not a fan thing, Blizzard is actually making a WarCraft 4 RTS.
Let's also pretend that you have not lost faith in Blizzards ability to create an RTS (or any game) that you like. Really try and root yourself firmly in the realm of fiction for this one- it's the WarCraft 4 of your dreams.
What does that dream look like? What would YOU want a WarCraft 4 RTS to be? What kinds of gameplay would you want to see? Do you prefer the WC3 formula with smaller armies, more individual unit abilities and heroes? Or perhaps you prefer the SC2 formula with large armies and zero to limited hero units? How about lorewise? Would you want the story to take place during the timeline established in WoW? (For example, missions of you commanding the armies assaulting the black temple) or would you want new stories? Within the WoW canon? Or maybe an entirely separate canon/timeline?
For me, I'd prefer a bit of a mix in formula, with some new stuff. I like heroes in the campaign, but for multiplayer I'd rather just manage armies, or have a map toggle to enable/disable heroes for games. I would want the unit cap increased regardless, maybe not to the level of SC2, but certainly higher than WC3.
Lore wise is trickier for me, on the one hand I would prefer it stay within the main canon. Using the RTS as a way to build up new characters for for the story. At the same time, having the RTS go off in its own direction could be an interesting take, and wouldn't necessitate each race joining either horde or alliance for gameplay.
Alternatively, scrapping both formulas entirely, and doing something new for Warcraft could be fun. Ever play C&C Renegade, Natural Selection, or Giants: Citizen Kabuto? 3rd person base building/RTS? That could be neat.
("I want something 100% new, not warcraft or starcraft or even diablo. Completely new." Is also a valid response for this. If you're in this camp, focus on mechanics, what kind of RTS would you want to see?)
(Whoops, sorry mods. Thanks for moving!)