Given that it's taking so long for Mechwarrior to come out, I wouldn't mind seeing a modern take on the old Earthsiege games. It has been a long time since we've had a good mech game on PC.
One thing I hope they do away with is the arbitrary ranges. Just make the speed and accuracy of the weapon determine the range, don't make it disappear at 1000m or whatever. Same with the mechs (or whatever they're called in Earthsiege). No arbitrary weight limits. You can put whatever engine the engine bay will hold, and whatever weapons specific hardpoints will hold. Speed should be a function of mech weight over engine power, not some predetermined speed based on a table.