Around 2001 I looked at the web based Multimedia Home Platform (MHP) standards for adding web like features to broadcast TV and was not very impressed. There is now Globally Executable MHP (GEM), a followup specification for adding web-like interaction to digital broadcast TV, IPTV and Blu-Ray players. I am also not impressed with GEM.
Like MHP, this is a formal set of standards (ETSI TS 102 819, ETSI TS 102 728, ITU Recommendation ITU-T J.202). GEM assumes the consumer device has Java and then assumes the makers of a class of devices (such as set top boxes or DVD players) define a set of features for such devices.
Like MHP the features of each GEM implementation has to be very carefully defined, as the devices will be produces in the millions and the communications media for broadcast TV and DVD players is very constrained and non-interactive. The consumer device can't simply request a different version of some content from the broadcaster or from the DVD disk, as the communication is one way. The consumer does not expect to have to keep upgrading their low cost box with more memory and software.
In the case of IPTV the situation could be different, as IP indicates "Internet Protocol" which is usually interactive. However, devices and series from the broadcast industry for IPTV tend to build the same limitations as broadcast TV in.
While I see standards such as GEM as being needed for enhancing broadcast TV and DVDs, I don;t see these as very important platforms or ones with large growth potential. The future web-like format for use on Internet-like networks is simply the actual web on the actual Internet. Rather than the Internet and the web constraining themselves to fit with the limitations set by old fashioned broadcast digital TV, I see digital TV being a legacy service on the Internet.