Change sequence settings while retaining framing and timing
Currently, if I receive a timeline that is 4K, and the final output is to be HD, and my computer can't handle the playback of the 4K sequence - and I go to sequence settings and change the timeline to HD (scale down), all the footage that was scaled to, or framed for the 4K screen will have retained its pixel size relative to the HD frame. i.e. a 4K footage that is scaled 100% on a 4K output (full frame), will still be 100% if i change the sequence to HD and be far too large for the new screen size - I would ave to go into motion setting snad change it to "50%" to fit. Even more work is to be done if the footage was reframed.
So, it would be handy to have a feature when changing the sequence settings where you can "retain framing (for scale cahgnes) and timing (for frame rate changes)" check box - in the sequence settings. That way you can change the sequence setting without having to go through every shot and resize and reframe them to fit into a HD output (or whatever the case may be). I suppose it would have to have the same pixel aspect and ratio to be possible, but I think that would still be useful.
Antoine Autokroma commented
Or just preview in 1/2 and output in 1/2 Premiere Pro handles that without going to 4K