The "core" hasn't updated much, so probably there isn't a lot of "need" for an update to the 1284 core, either.
An add-on version compatible with 1.5 build system would be nice, if that has "finalized." (but last I looked, it wasn't great for targets that wanted to share some of the "core" core code. (although perhaps one shouldn't care, and just do a separate set of core files anyway?))