To add to Keegan's reply: be-tarask is already renamed, which sets a good and long-awaited precedent.
It is not entirely complete, though, as there is at least one technical issue remaining:
https://phabricator.wikimedia.org/T112426 . AFAIU, it is supposed to be resolved by Wikidata developers. It's rather important and I prefer not to rename any further wikis until there's a known way to resolve it.
bh -> bho
eml -> egl
als -> gsw
nrm -> nrf
And also a few others, though they will require consensus building:
simple -> (not sure what; see another thread)
no -> nb
ku -> kmr