Should the Mass Effect IP branch out into other genres?

An RTS would work but I could definitely see a Mass Effect themed X-Com like game. Turn based missions with a strategic part where you build up your dreadnought and do stuff on the galaxy map. That could be fun. They could bring in more named characters and character interactions within the teams to give a more mass effect-y style.

Also, the obvious genre-change would be to make a Space Sim out of it (there was even a decent fan game once, though I think it was just developed by one single guy, might have been called "ME: Alliance" but not sure).

However, in the end, for me the perfect solution would be bring more elements into the game formula that they have right now. I know they tried to add the space sim factor into ME:A and failed horribly but in principle, I don't think it's a bad idea necessarily.
Also, I could see them using more adventure and puzzle elements in future ME games. They have everything they need to do it already (the scanner, an inventory, a dialogue system, a research mechanic to craft/build/combine stuff) but they didn't really use it, despite the fact that they had quests for it (like the murder investigation on Kadara for example). I'd say, a puzle element here and there could be a nice addition. They'd probably need to make them an optional path since not everyone is going to like the down pacing this wuold cause but I'd be thrilled.

Would ME work as an RTS? I don't think it's a horrible idea, but I wonder how it would actually work. Also, would it appeal to the audience who plays ME games? That would actually be the question. Is there a market for it?

I'm not into RTS.  If there were any branching out, I'd do an RPG set around the First Contact War.  If well written (always the issue, right?), it could be interesting, showing us how humanity was introduced to galactic society.

Mass Effect Online

We're back in a post Reaper Milky Way rebuilding
Choice of playable races Human, Turian, Asari, Quarian, Krogan
EA gets their cash cow. Bioware gets to put together a solid rpg
Bioware/EA will be hated by "loyal" fans (but that's nothing they can't handle)

A ME RTS timeline would be nice; Rachni War, Krogan Rebellion, First Contact, Shanxi, etc (aka Starcraft style) with different protags / races relevant for each mission / story.

Mass Effect: The Telltale Series.

I like the idea of a RTS game. Maybe something during the Contact War.

Also, keep a story with character creation and decisions between missions.

And I can see a spin-off game just after the war, with humanity first meeting the other species and trying to find their place. There is potential for a few cameos as well.