I think Blackstar characters from the toyline would fit quite well into the MOTUC line as a monthly bonus figure on occassion. It would probably be the only toyline I'd be okay with merging into MOTUC. Blackstar wouldn't be popular enough for its own toyline. Thundercats is popular enough for its own line.

They reused Blackstar's dragon Warlock in the He-Man cartoon show as a generic dragon, so maybe if they got the Filmation rights to He-Man, they could make the dragon.