In an interview with PCGamesn, Rosewater said, “Interestingly, the modal double-faced cards (MDFCs) that most give Zendikar Rising the adventure card feel were actually created during the design of original Innistrad when we first played around with double-faced cards."
Rosewater went on to explain why Zendikar Rising's MDFCs all feature a Land in the back: “As Zendikar is a world connected mechanically to land, we decided to give it the MDFCs that all have a land on the back," Rosewater said. The biggest change MDFCs have on the game is they let you put a higher concentration of land in your deck to help make sure you get enough mana in the early to mid game.”
This suggests that future sets like Kaldheim and Strixhaven may feature MDFCs with other card types in the back, not just Lands.
Rosewater went on to confirm that these two sets will feature new MDFCs.
“I’d been waiting for the right time to use them and I finally found it with[…] Strixhaven (a set coming out next year). I was asked to do some advanced design work and I realised that the mechanic was deep enough that we could use it for all three sets of this upcoming Magic “year” (Zendikar Rising, Kaldheim, and Strixhaven)”.
Kaldheim, a Viking-themed set, will be released in January, and Strixhaven, School of Mages, will be about the most elite university in the MTG multiverse.