There definitely is interest out there for RTS games. If not, StarCraft would never have gotten a remaster. Of course SC is mega-famous and one of the original e-sports and still played competitively so... yeah, it's not like they are trying to revive forgotten titles because of new interest. Still, it shows that people still enjoy this type of game.
I think the single most important thing is going to be the interface and how everything feels to control. This genre is notorious for making the player perform repetitive and annoying tasks, while your units trip over each other in some other corner of the map. I've thought for some time about how to make an RTS that is more heavily focused on strategy (i.e. placement of buildings and armies, unit abilities/combos/counters, build orders/research paths) than on mechanics (i.e. remembering to go back to your base to click on a worker and send them to mine every 5 seconds for the entire 2 hour game).
I felt that one way to accomplish this might be to reduce the overall number of units and/or buildings as much as possible.
The reasoning for this is pretty simple: Fewer units are theoretically easier to control, both for the human and for pathfinding. It might also help to keep the resource numbers small-ish. It is tempting to allow players to build hundreds of units and mine thousands upon thousands of resource X, but the superficial coolness of the big numbers will wear out fast. Keeping things manageable will make it easier for players to quickly understand and react while playing, and hopefully reduce the overall number of clicks needed to make stuff happen.
I'm not the biggest fan of walls and I felt that StarCraft really benefitted from not having them. You could blockade using buildings but none of the buildings were strong enough to hold back a full attack... this encourages focusing on army movement and active play rather than just bunkering behind walls.
Automating resource gathering is a plus in my book. As a player I want to be making choices about how many workers to build, and where to send them. Searching around the map for idle workers is just annoying. It makes sense that if a resource patch is depleted, they could go idle. But I should be able to set a waypoint so that every worker that pops out immediately goes to mine there.
Pathfinding is probably the most technically difficult aspect, it's going to be expected that units can navigate around obstacles. The more robust it is, the less often you'll have stray units going on vacation (or just getting stuck at home), but this will have to be balanced with processing time.
Anyway those are my thoughts as someone who enjoyed quite a lot of StarCraft but got really exhausted with the insane amount of clicking/button pressing/frantic scrolling involved.