When the new edition rolls around that swaps to the new type, I expect a bunch of libraries are going to get really annoying to use. And vice-versa for new libraries with the old editions.
Both types have the `From` conversion traits implemented between each other, so in most cases interoperating with APIs using the old type should be as simple as doing `(1...4).into()`. And, probably because of the warts of the old types, I haven't seen them used much in APIs, so even that I don't think will happen very often.
Unlikely, since library interfaces need to use a trait to accept all of the open/closed inclusive/exclusive syntax variations. If the only accept one specific named range type, they're clunky already.