In digital broadcasting there isn't really any such thing as "an interlaced channel". Just a coding standard and a bit rate. I don't have a citation to hand but it's probably easier to get a good picture at a lower bit rate when you start with a progressive source. As 1080/50p (and 60p) equipment becomes more readily available I think it will become standard for originating material. Hence removing the compomise between 1080/50i, 720/50p and 1080/25p. And the 60Hz related equivalents.
In the set of SMPTE standards for handling full bandwidth HD digits there are 2 basic bit rates, 1.5GB/s and 3GB/s. The latter is needed for 1080/50p and 1080/60p where the pixel clock is 148.5MHz. All the others (1080/50i, 720/60p and lots more) fit happily in 1.5GB/s with a 74.25MHz pixel clock. To add to the proliferation of standards all the 30Hz and 24Hz related standards have a variant with the pxiel clock multiplied by 1000/1001 to fit with the 59.94Hz NTSC field rate. This has always caused trouble with timecode. Now that NTSC is just about officially dead for broadcasting I can't see any reason for originating programme material on these standards.
NewVista's sketch is not unlike 1080/24psF. This is effectively 48 Hz interlaced int he channel but carrying 24Hz progressive. This allows material originated at 24Hz to be displayed on a CRT monitor without undue flicker.
Standards, don't you just love them. So lets have lots of them
