Actually, Disney World is required to return MSEP to
Disneyland sometime within the next year, per the deal they made to get it over there in the first place. So, yes MSEP will return to the Disneyland Resort, which park, who knows? But it will return, there may indeed be some legal issues in brining it back to Disneyland, since they sold bulbs and tickets to the final show at Disneyland, but I am sure Disney would find a way around that.
Disneyland does need something else at night now, given the popularity of Cars Land, there are more people coming to the parks and during Fantasmic! and the Fireworks, times when the lines have typically been short for attractions are now longer than during the day, so they could use one more item to keep people busy at night.