I have clocked in around 2 and a half hours of Research across a couple websites including Star Wars Wiki, the list below is the best of the Idea's i have for new Imperial Remnant units.
Land:
Imperial Commando's.
There are many Types of Commando's in the Empire, one of the most coolest types is the Imperial Commando Special Unit Division, Darth vader formed them for one mission only, to hunt down the Last of the Jedi and hunt down renegade clones, they fit in very well seeing that the Republic has Jedi, and seeing no infantry i have seen can really beat a single jedi with out having a mob of units lol. Special units could really bring good RTS to the Land combat game mode. Other Commando's can be found at this site
starwars.wiki.com/commando
Sharpshooters. (Snipers)
The Imperial Army always had Sharpshooters in their Army core, for long range targets, they would add some more firepower to the Remnant's Land forces.
Engineering squads.
Engineers were Standard in the Imperial Army, they were equipped with standard weapons, but also had thermal detonators, medpacks or portable sensor arrays, They could act like difflers for the consortium, they could be made at the Command Center in squads of 4 and can be used to take out large objects like Tanks, or structures.
I'll have more unit idea's in due time, just trying to find the time to research some more lol. I hope these help and add to the creative design of the mod.
Thanks for reading!