I agree with you that such a thing would be really nice. But I think that for a somewhat long program (say, a half hour or hour of TV-like coverage) it's overkill. As long as the framerate can be kept over 30fps and there isn't a lot of "lag jumping" and warping in the replay, the video should be plenty good enough. I'm 90% positive that I could record good quality video on my home machine without a problem at the resolution you suggest. A hardware based capture card works wonders.
Actually, I mostly watch SPEED. They have a ticker on most of their race coverage including Speed GT, Speed Touring Car, American Le Mans, etc. It constantly scrolls the names and numbers of the cars along with their positions. It also has an indicator for when the track is under a full course caution, and it sometimes shows the leaders for each class in ALMS.
The rendering system you describe would be nice, but I think i'll be old and grey before we see such a thing. It seems to me that it would be just as easy to just render a ticker using data from the race. Then, that could be overlaid on the video using video editing tools, similar to what a real TV station might use.
I still contend that the really hard part is the camera work. A single race lap might take shots from half a dozen track cameras, a forward facing car camera, a rearward facing car camera, etc. Then there are cameras in the pits (not much to see in LFS at the moment in that regard) as well. Getting all of these shots in LFS is VERY time consuming. Hence, most of the LFS videos we currently see are either very, very short or they're longer, but taken from very few camera positions. Following a two car battle for the lead in LFS, over the course of a single lap, would take a long time. Doing it for a whole race, then adding in extra camera views, slo-mo replays of accidents, etc. is going to be a huge undertaking. I can see it taking months of production and some seriously good video editing tools just to cover a single 25 lap race in this "TV style". I'm VERY curious to see how STCC does their videos.