If we're on the spec of 7 originals and 3 IPs, the 3 IPs would need to be big. Conjuring definitely fits this bill, as well as Candyman (assuming the reboot is successful). Being that it seems Horror Made Here is effectively dead, a big one like IT or Gremlins would be great to see. However, I remember the spec for Thirteen Ghosts at the end of HHN29, which would definitely make an interesting house.
UCM is technically an "IP", but I could see them classifying it as original and bringing it back.