It's long past due that we should move to software which isn't maintained - because there's nothing to do. Adding features could be done either by writing a new one - because the requests don't really fit the meaning of old one, the creators saw that and rejected; fixing bugs - yes, fixing bugs may remain, but are there many bugs in, say, TEX code?

We don't yet know how to write a completed software well - the one which isn't updated on Github for years yet nobody calls it stale or outdated.