If Mass Effect 4 Were Battlefield 4
Here's what Battlefield 4 might look like, if it were done in the aesthetic of Mass Effect 4.
If Battlefield 4 were Mass Effect 4, it'd probably look like this poster (click on the image to view full-size), which was designed by a talented deviantartist going by the name of Scotchlover. Like the original Battlefield 4 artwork it's based upon, the poster depicts the protagonist of Battlefield 4 running towards the viewer. Instead of Bradleys in the background, there's three Mako ATVs. And instead of a modern-day rifle and handgun, the character's carrying a sniper rifle from the Mass Effect series and a matching sidearm.
The best thing about the artwork is the armor he's wearing, which appears to be some variation of the N7 Spectre armor worn by Shepard. It'll no doubt serve to offer him much more protection than modern day battle armor would.
Scotchlover, if you're reading this, know that I love scotch, too. What's your poison? I'm all about the single malts.
In my opinion, playing Mass Effect 4 in the same universe as a civilian or mercenary would also be interesting. Seeing the story unfold from a non-military standpoint or even playing as one of the non-human characters and seeing how they interact with their own kind would be a treat for every Mass Effect fan.