Analogue TV signals are being switched off in Europe and replaced by DTT only, so most of the old analogue cards are being dumped for peanuts. October 24 is the date of switch off here.
Most (if not all?) of Europe now has DTT, so there is no use buying an analogue device for TV reception.
Aus is also well on the way to complete switching to DTT, as I understand it. Not sure about other locations.
dvb is used on the PC in place of v4l2 for DTT.
The cheapest, by far, DTT compatible device, is the USB, at least at present.
Maybe the cards will drop a lot, but I doubt it. To be of any use they would need to be MPEG-2 and MPEG-4 compatible, as well as being capable of decoding full HD.
I think their days are numbered, except for the higher-end cards, or maybe the real low-end cards that have no decoders on board and just pass the mux straight through to the OS, as the USB devices do.