I wonder about they are testing our reactions and feedbacks to plan the revival of those legacy settings. Mystara can show off about the no-FR D&D what was a smashhit for its day: the arcades "Tower of Doom" and "Shadow over Mystara", even with a remake/remastered edition.

Mystara also has got pieces of steampunk, pirates & mutants (Savage Coast/Red Steel) and Jurasic Park&Hyrboria civilitations (Hollow World). If my memory doesn't fail Mystara has not canon lore about the crystal sphere, and even it may be "visited" by aliens out of the rest D&D universe.

We know the revival of Dragonlance is welcome. Even I would dare to say maybe in the future we could see some CGI cinematic trailer like the ones for Magic: the Gathering. After FR the next D&D world in M:tG may be Dragonlance, in 2022.