With Monster High making a comeback I'd love to see more Monster High characters/sets in the future. I always loved the character packs and was so disappointed the line ended before Howleen was ever included in the lineup.
If you do start making Monster High Mega Construx again, I have a few suggestions.
1: Keep the minifigure design the same as before. They're perfect as is! <3
2: Please design nicer sets with the same care and attention as you've given the Masters of the Universe line.
Monster High itself is a castle, and you've been designing castles forever! I know you can design better sets for MH.
Something I would personally love to see is the dark version of Howleen from 13 wishes, on throne, with dark versions of all the MH girls she wished away (as well as Whisp of course).
3: More characters. It was nice you finally got around to doing a few of the mansters, but sadly MH was cancelled before you made more than one or two of them. Aside from the rest of the mansters it would be nice to see the school staff such as the lunch lady, and you could make classroom sets that include the teachers.