Gigantisaur is probably THE concept figure that "never made it until now" that I'd like to get the most !
Unfortunately, we probably won't get many vehicles in MOTUC, let alone playsets. Heck, even Castle Grayskull is not sure to be made...
Mattel's total lack of faith and ambition for MOTUC is a real sad thing to behold.
If a gigantic item like Gigantisaur was made into a MOTUC beast, it would certainly be the crown jewel of my collection ! The same goes for the Eternia playset.
I'd like for us to get ALL the Preternian dinosaurs : Gigantisaur, Tyrantisaurus Rex, Bionatops, Turbodactyl + Battle Raptor (MYP cartoon) and maybe Battle Bones.
Preternia is the PREHISTORIC Eternia, and prehistory without dinosaurs is an absurd thing. We have Tytus and Megator, we have He-Ro, we have King Grayskull, we even have Preternia Disguise He-Man... I say now bring on Eldor and the preternian dinosaurs !
The reason we didn't get any dinosaurs yet (or Monstroid or Mantisaur, for that matter) is because those beasts use a lot of tooling, and that Mattel made it compulsory to reuse any tooling. Once again, it comes down to Mattel's mistrust and lack of faith in MOTUC, and also to their stinginess. I don't think we'll be able to change that, but I still keep the dream that someday we might get some of these items in MOTUC. Who knows ? After all, all it could take would be a change in Mattel's management, and the presence of someone who really likes toys (unlike the current directors and CEO, who come mainly from the food sector and from the oil industry) and who would feel the nostalgia and remember the initial grandeur of the Masters of the Universe franchise...