For all skeptical out there, executive producer Casey Hudson and Community Manager Chris Presley have repeated over and over both in the official BW forums and Twitter that the SP will be the best of the franchise yet and that it is the core of the product, multiplayer is an optional addition that you can use if you like it, nothing more nothing less, it's not going to detract anything from the SP and it was developed separately by the Montreal studio under supervision of the main ME team.
Really, some people are so fatalistic.