With the new concepts Wolfenstein: The New Order has introduced, I think its easy to say that the game has the potential to be an RTS game.

A Good premise would be that the Resistance has grown larger but still operate underground. They no ability to liberate a nation in their starting missions but through discovering other Da'at Yichud vaults, they become stronger and stronger. Few in number but powerful individuals. Nazis would be the usual shock and awe. Striking fast and hard or slow and precise, they resolve conflicts through the force of their massive numbers.

When a Nazi spy manages to slip through the ranks of the resistance and manages to gain information about the other Da'at Yichud vaults, the war has turned into a race of who gets to these vaults first. Smash and grab would be the main style with story missions here and there to expand on characters, lore, etc.

Nazi base building would be strong, permanent, and stands as a defensive structure on its own. They start out powerful but slow but they eventually go weaker to some extent but faster. Resistance base building would be weak, defenseless, but incredibly fast. Having the ability to relocate aswell. That is, until they're able to reach a Da'at Yichudesque level in their tech tree. Once they do, they'd be equal to the Nazis. Permanent strongholds with powerful defenses and the like.

Nazi resource management would revolve around setting up prisons and whatnot. Sort of like a Black Market or a Supply Drop from Generals. A Self sustaining economy, if you will. Resistance resource management would resort in scrapping any material they can find in the battlefield. Alternatively, though it maybe later in their tech tree, they could establish an espionage center of sorts in which they could steal resources <self sustaining economy, no more hunting for scraps>, information <revealing them in the map>, or technology <adds additional units>. Though I would assume that there would only be one available espionage center per game and when one function is on, the others are disabled permanently.

I continue to talk about mechanincs, online gameplay, boring stuff. Didnt bother to add.