The MSEP is not coming back. DL is getting a brand new light parade as soon as 2014, and WDW let SpectroMagic rot (as stated above) and have nothing to replace MSEP with.
MSEP itself is falling apart itself because it's OLDER THAN DIRT. WDW's crappy maintenance (or lack thereof) hasn't helped the situation. WDW will run it until it falls apart, and then they will likely just not have a night parade. I'm sure their new daytime parade (2014) will be able to run at night, much like Soundsational does now here at DL.
MSEP is NOT coming back to DL. And NO ONE should want it back. It's a technological relic that presents an easy way out for Disney. Be excited for a new light parade using cutting edge technology and including characters that were introduced after 1977.
The poster above me has it right. I can't tell you how many CMs have told me it's coming back. They're wrong. We're getting something much better than the Night of the Living Electrical Parade.