Er, how long's a piece of string? Until hell freezes over? My old Yaris came with DAB as an option in 2009!!! And I loved it (6music on the move, hooray!). It was one of the things that really made me think twice about moving to the panda. But the panda's more fun in so many other other ways
Sod's law says you'll have to wait until about a month after you've bought your new cross before they start fitting it as standard.
I just ordered a Cross and asked my dealer specifically about DAB who did a little digging for me. As far as he ascertain, there are no plans to introduce DAB as standard in the near future. But he did warn me that Fiat could change their minds on a whim, plus they do bring out special versions' from time to time which could feature an upgrade, although this tends to happen with established cars or those coming to the end of the model and is probably not a priority for a newish model like a Cross.
My decision was to go ahead and get the car and then look at third-party/aftermarket module such as the Pure Highway range at a later date. But in the short term is to do what I do in my current car and use my mobile phone to receive digital radio via the mobile network (e.g. BBC Radio Player) and listen to it via the aux socket. I get good mobile reception on my drive to and from work and have an 'unlimited' data allowance. I should say though that I work for a mobile network, but it may be an option.
Having said all that it will happen exactly as GL said an Fiat will announce DAB as a standard option just as soon as my brand new car rolls off the transporter!