Let's think about this rationally for a moment. What really separates SP from MP? In both cases, you shoot things, use abilities, complete objectives, etc.
What makes MP unique and superior to the SP garbage is the human interaction. It is the fact that one is not alone but has real people around them even if those are far far away in the real world. That is an amazing achievement and it is the essence that breathes life into the whole Mass Effect experience.
Therefore and with that fact in mind. I propose to distill this most valuable aspect of the MP experience. It should be the real focus, the core, the centerpiece of MP, in order to make it even greater.
And where better to interact than in the lobby, without the constant distractions of annoying enemies that need to be eliminated or combersome objectives that need to be fulfilled. The lobby is the place where you can concentrate on the awesomeness of the social euphoria that is MP.
Therefore, I think BW should not only remove SP but also all MP gameplay except for the lobby, where players can chat while waiting. Prune it down, cut the fat if you will, to reveal the epitome of what makes this game great.
I also have the statistics to prove that this would be massively beneficial to BW and EA, both in terms of popularity and financially. Around the world, 75% of people with access to global communication send messages regularly in one form or another. On average, 85% of the worlds population have access to communication devices, such as cell phones or computers. This means 63.75% of the world's population are engaged in sending messages. That's roughly 4.75 billion people that are all a target audience for the streamlined MP lobby. Compare that to the meager 7-10 million copies of ME3 sold and you'll see to what riches BW?EA would be headed if they stop scaring all those people away with their frantic, pretentious and frankly unnecessary gameplay.
It will be glorious.
As a possible DLC, I envision an appearance pack that changes the lobby's layout to a classic MS DOS prompt style or an added feature for Kinect gesture recognition. Do it BioWare, your future - and ours - depends on it.