Teletext is pages of text information imbedded in the OTA broadcast stream, which was useful, sort of, before the internet and HTPCs. It could contain all sorts of information, like weather reports, news headlines, and . . . well other stuff.
I was always clunky to use, didn't show much info per page, and for me at least, not more than a passing novelty.
I don't think supporting teletext is much of an issue at this time, or into the future.