Hi Warner, no, I don't know why development seems to have come to a standstill. I worded it like that because programming in general requires focus and inspiration (among other things).
Yes, support for popular new formats like HEIC en WEBP (and new camera raw formats) would be great to have.
The combination of database, file manager and image editor (plus metadata editing, batch editing, slideshows, printing, catalogs, etc) is still rare... there are alternatives, but to my knowledge none that do all of these things.