So the plan for the next couple of versions is set:
Version 6.9 will add new Tier 3 Aircraft and hovercraft factories and units built from them, about 2 dozen more units altogether. Also planned is geothermal and moho upgrades, jammer towers, and also LOS (Line Of Sight) towers built by minelayer vehicles.
Version 7.0 further in the future will be all about the addition of a resurrected and renewed race, The Lost Legacy originally by M3G. This is a huge project and will take a while, it's a good thing we've already started on it. You can view progress here.
For more details, visit the Total Mayhem 6.8 TAU forum topic here. ...or just scroll down for the download!