There's been some light rumor of a modified version coming to WDW (I believe the 18 wheeler Cars float is too big for some MK turns), but i'll believe it when I see it. Disney has actually acknowledged people talking about MSEP coming back on social media using "shifty eyes" emojis. This leads me to believe it'll be announced during the D23 event in November.
DL Magic Key holders seem far less satisfied currently than WDW AP holders from what I can tell and with insane price increases, penalties for not showing up for a reservation, having to pay for parking every time, no new attractions/entertainment, and no Fantasmic or World of Color, etc, I think MSEP is more or less a way to throw them a bone.