I think that could be released in summer.
Sh4 was the same engine with changes, including sh3 files and iīm sure that sh5 is the same thing but improved , like some mods (torpedo room, engine room) but made for the devs.
if this could be made for modders is sure that they can do the same and better because they have the tools and the source code, so i donīt expect too much delay
ps. i never play careers until the game is fully patched and the first big mods packs are available