Manufacturers seem to have stopped building SD only equipment. It doesn't make much sense to have the same equipment in two versions - it's easier and cheaper to offer a single SD/HD device. The equipment cost of HD is really not much higher than SD at present as far as I can tell. The big cost is the rebuild to make a production studio or master control into an HD operation. I think that over the years all the English and French networks will convert to HD because the cost will not be more than SD. The timing for HD in some operations will coincide with the need for a general technical plant rebuild. They will accumulate SD/HD equipment and operate it SD in the beginning as part of the old plant then switch to HD when they rebuild....
Here in Canada I suspect that some small market digital services/channels will still be only digital SD ten years from now.
Low cost HD cameras (sub $10,000) are available now and offer good performance for many purposes. A small market TV station could easily use this equipment for local news and programming. These cameras record on SD cards which make them easy to use and eliminate the requirement for a real time transfer into an editing system. Just put the card into the computer and away you go. In small operations, Adobe Premiere Pro or Final Cut Pro can be used for editing. The Premiere software bundle with other useful programs is less than $2,000 and it will run on a PC with less capability than a high-end gaming machine. A lot of programming on specialty channels is shot using this kind of gear.
In 2000, HD was a really expensive proposition but over the last decade the costs have come down dramatically. The only reason for SD in 10 years will be to save bandwidth on a BDU.