On a technical level, providing, for example, combined DRM/DAB+ receivers is not an issue for many device manufacturers, as the core receiver chips already support those standards simultaneously. It therefore is merely a question of UI design – and clearly expressed market demand. Both standards are “open” which means that the technologies are freely available and there are no secret algorithms, legal contracts or IP costs that need to be taken care of. Combining open and proprietorial standards is therefore much more complicated and costly.
Nowadays much is made of software defined radio which in principle can decode and offer both analogue radio services and any digital radio flavour but this does not mean no costs, no hassle and no effort. The main thing is the demand as chipsets and technical solutions are already available.