Hi. I'm the sole UI3 developer. I have no plans to do a new interface or a major redesign of UI3. UI3 is a hobby project for me and I'm quite happy with its current state, for the most part. Besides, major changes tend to require changes in the
Blue Iris server, which I do not and never have had any more access to than any other customer.
As for the Blue Iris local console, I wouldn't expect any major changes there either. The GUI changes for v6 are mostly done already since 5.9.9.8x as far as I know, and consist mainly of color scheme changes. (same for UI3; it has some color scheme changes that will appear when the Blue Iris version ticks up to 6, and can be previewed via UI Settings > General Settings > Color Theme)
Blue Iris has been essentially a one-man project for its entire 25 year existence and he doesn't have the resources to to major redesigns every few years like Ubiquiti does.
H.265 playback in UI3 may be coming soon, but that is not exactly a feature worth sticking around for. If you're interested in the design and features of Unifi Protect, get Unifi Protect.