[...]
As mentioned, the question is open whether or not the package should be
added to ELPA or not (I prefer adding it to ELPA, but I am biased).
If you prefer adding it to ELPA as opposed to adding it to the core, could you expand a bit on why you prefer that? It seems remarkably stable, pretty amenable to external expansion, and apparently has all of the assignments lined up (I had thought this was still incomplete, personally), so I would expect it to be a good fit for core. That said, I haven't looked at the matter closely.
Thanks,
~Chad