Pfeffersack
Deity
Would it be possible to allow players to upgrade their regular units to hidden nationality? If that seems unbalanced, probe teams could be used to expose the nationality of a unit for a turn.
That's already possible with two special abilities: "Wild" (for native units) and "Irregular" (for normal units)
Also, any possibility of new unit types (tanks, motorcycles, large bombers, etc) that weren't in SMAC?
The unit workshop will not return because of technical issues and the huge problems the AI would have with using it. Instead special abilties and promotions serve to provide the specilialization. Maniac has added (and probably will add in future, IIRC the Battle Ogres are planned for example) several new units in the past, if they fulfilled a special need or added something cool not covered by special abilites/promotions - so it is best to suggest a certain new unit design. Even if that design wasn't in SMAC, it has a chance to make it in Planetfall, because it is not a 1:1 conversion, just a mod inspirated by SMAC.