They will, yes, because it's the most sensible solution. Constantly broadcasting information with the video and audio signal no longer makes sense. It would make more sense to use that bandwidth to up the bit rate of the video and audio.
Teletext is an afterthought of how to use the time during the vertical blanking interval of a CRT display, where a beam was swept as you look at it left to right, top to bottom. The time it took to reset the beam (horizontally and vertically) is called the blanking interval, and in that time, the data in the air went unused, so some clever clogs decided to stick some information in there that could be picked up whilst the beam was being reset, in the case of teletext, the vertical blank, which would take quite a few lines on the TV screen in terms of time to do.
Modern flat panel displays don't work like that, they don't have an electron gun raster beam, so it makes no sense, and thus with a digital signal, it makes no sense.
Old teletext however, and these figures are not factual, just illustrative, was never fast without memory in the TV to store them. The data was being transmitted constantly, page per page, so say if there were 999 pages, and there was space for 50 pages per second, each page would get broadcast every 20 seconds, so in the worst case scenario, you would have to wait 20 seconds to get at the information that you wanted. Hardly rapid was it?