Providing SD in MPEG4 is possible (see the PI channels on "HD" satellites). So the complaints from customers not wanting to downconvert 16x9 can be met by continuing to deliver the 4x3 feeds. DISH does this with their MPEG4 "Eastern Arc" service. SD in MPEG4 doesn't take up a lot of room on a satellite. But getting customers to change equipment when there is a financial incentive in place NOT to change equipment is an uphill battle.
Quite so on the disincentive!
Heh: There will be complaints! "The picture is much clearer than before, but I don't like it....."