The inevitable move to 1.15 Minecraft is coming closer and closer but I can't help but wonder, Will that cause a DMU reset or are you going to use the same world?

Just curious :P

There will be multiple servers. No reset, not using the same world from 1.12 in 1.15. 1.12 servers will keep running along side 1.15 until no one plays on the 1.12 servers anymore

would there be a way to import my 1.12.2 TARDIS onto 1.15? I, and probably a lot of players, have spent a very long time building a custom TARDIS. kinda seems like a waste to lose it all when we update. I've even spent some time preparing my TARDIS for 1.15

All the block IDs are different in 1.16. We've rewritten the mod from scratch. 1.12 builds with modded DM blocks will not be compatible.

Mojang changed a lot between 1.12 and 1.15 it's just not possible to convert them. At least not easy