From a purely British POV I simply can't see the point in investing the amounts the BBC is investing in DAB coverage only to indefinitely duplicate four of the same channels on FM (and a fifth on AM). It might not be this decade, but I do think we should switch off the UKs national FM networks eventually.
That's not to say the FM band should fall silent, far from it. FM is perfect for local, small scale and community broadcasting and switching off the national FM networks would give much more space for this. A really radical future might include open access to at least part of the FM band, with the only regulation being power output and basic taste and decency rules. I'm not sure British regulators would go that far, but there are plenty better uses for FM than bandwidth heavy national networks rebroadcasting what is already on DAB.