The problem with DAB is that the government pushed it too hard before it was a mature enough technology to take off.
It was launched and broadcasting a decade before a significant number of people were listening to it and with 1980's MP2 codecs that provide mediocre sound quality yet aren't efficient enough (even at low quality levels) in their use of the spectrum. This has made it costly for radio stations to broadcast on DAB and discouraged serious listeners for whom sound quality is important.
We are now faced with a decision to soldier on with the cr@p system we currently have and hope popularity will pick up or alienate the "early adopters" whose DAB sets don't support DAB+, switch to DAB+ and hope they make their investment again.
I see in-car listening as about the only sensible application for DAB. Sound quality isn't that important in a car for most people, you can have a respectable antenna installation, so affording the set a decent enough signal and DAB gets around mobility issues nicely without retuning.
Around the home, the quality is too poor, IME, to replace FM as a "Hi-Fi" source and the reception possible with "kitchen window-sill" type sets without an external antenna renders them unlistenable IME.
In the meanwhile, you can pick up an internet radio that connects via your Wi-Fi network and streams any radio station in the world to such a set with comparable sound quality and a perfect signal... Or you can listen via satellite TV, or terrestrial DTV, or on your computer, all without making a further investment in hardware. DAB has missed the boat as far as home use is concerned.
So, if it's in-car use that will make DAB take off, how many new cars are fitted with DAB radios as standard? How long will it be before "almost all" cars have DAB capability? If you take your car abroad, will the radio still work?

Kevin