Domination (cmon, it ain't that difficult)
AMP / scriptable entities
updated engine/renderer (XReal probably)
bug fixes. LOTS of bug fixes. Seriously, did you know you can blast/luci through patches from a certain distance?
basic bots, just good enough that they can build, defend and attack (and actually win without free funds and such if their opponent sux)
actual in game tutorial
minimap
a god damn release, and more regular releases with whatever updates there are
There have been projects for almost everything in this list, several for some of these, and they have all died...
also, some smaller things so mappers have more freedom: limited jetpacks, power/creep range limited by walls, cylinder/capsule shaped bboxes, improved alien swimming ability
And yes, I do realize the chances of any of those actually getting into trem in the next decade are very small.