It's great to see life being breathed back into CI again and plans are being made for future versions.
What would be useful in this debate is some kind of a high level strategy/roadmap for CI4 and an approx target release date. The time taken to release this will obviously depend on the features/updates to the code base. However saying it'll be ready when it's ready brings back really bad Ellis Labs memories. Is there at least some target date in mind? Based on this date it'll be easier to see how this fits into PHP version support.