A film or television show set in the Mass Effect universe (done well, of course) is probably what could bring it into the mainstream. In fact, the best bet would be to not even include Shepard or any of the game characters. Keep them to the games. Use the other media as an opportunity to expand the universe, and build the brand.
Agreed. Done that way, they don't have to rely on people already knowing or having played the games. Rather, they can focus on developing their world even further, without distractions for anyone who aren't already familiar with the series, but that the TV series could eventually offer some plot threads for future games based on what's seen on TV.