It's quite possible to broadcast teletext on digital services and that is done widely at least through Europe. The UK went for MHEG as a replacement. I found teletext faster and often fuller in detail than the equivalent digital services although the pictures are better on MHEG and it has the ability to embed broadcast streams (sometimes loops and sometimes live).
At least the TVs I worked on received MHEG if they were set to UK and teletext in other settings.
It's also done here in the United States. The Public Broadcasting Service has a for-profit arm called "National Datacast" that serves up a nationwide bitstream over the blanking interval of local PBS stations.
Disney tried a failed pay-per-view movie service over it. Some digital sign companies use it for loading new content. Microsoft tried a line of toys using the data stream. And I think TV Guide runs on here as well.
That's coming. MHEG is going be replaced with hbbtv (a html sub-set). MHEG is too difficult to write and has a small number of people who understand the weird syntax.
At least the TVs I worked on received MHEG if they were set to UK and teletext in other settings.