At the State of College Hockey Press Conference, Steve Chapman (Executive VP St. Louis Blues) Alluded to "another University is talking about going D-1." He made it sound like it would be in St. Louis. Maryville and SLU (SLU was a CCHA member from 1971-79) are the two in St. Louis Metro, Missouri, Missouri State, Dury (shares arena with Missouri State), and UMKC (doesn't have a ACHA team).
Maryville is the logical choice on who Chapman is talking about with maybe St. Louis coming back. Maryville plays in a 2,000 seat arena that could be expanded to add a sheet with around 4,000 seats, or Maryville could share The Centene Community Ice Center with Lindenwood. St. Louis plays in both Maryville University Ice Center (Maryville) and The Centene Community Ice Center (Lindenwood). Chaifetz Arena on SLU's campus doesn't have ice making ability.
UMKC has two arenas in the area (T-Mobile Center, and Cable Dahmer Arena) but no ACHA team, so this is highly unlikely. Mizzou needs an arena and would love to see A Walton or Kroenke help fund and build arena for them. There ACHA D2 team looks to be a decent team that moved up from ACHA D3. Missouri State and Dury are the ACHA D1 teams but would need a bigger arena they could share.
If any school makes the jump, I'd put money on it being Mayville.