I'm not a big fan of 4K, as it's not a 16:9 format; I'd much rather see the market shift to 2160p, then to 4320p....if they go to 4320p, that will be the day, as 480i, 480p, 720p, 1080i, 1080p, and 2160p will all be able to be scaled without any "filler" pixel (or pixels cut out), as 4320p is the lowest-common multiple of all those formats....of course, 480i/480p would have pillar-boxing, but that's not big deal, and to be expected.
The only one that would be a little off would be the widescreen version of 480p...but who's going be complaining about W480p by then?