I was reading up on the possible use of DLNA a little, and I hope it doesn't go that way at all.
I've gotten it to work for some things but it's a mess. The biggest problem is it's a Chinese menu, DLNA server manufacturers pick and choose what features they want to include and how they want to do it and DLNA player manufacturers pick and choose what features that they want to support and if one or both leave out something you need you're just out of luck. The right way to do it is to set an actual standard i.e. "you
will include all of these features and implement them this way if you want to claim DLNA 3.0 certification". That's a standard and as new features are developed you create a 3.1 or 3.2 standard. If you look at networking standard you'll see that an Apple will talk to a Cisco which will talk to a D-Link which will talk to a Dell. That's because the standards are set in stone and nothing changes until a new standard is agreed to.
You could use DLNA to stream video to computers, appliances, tablets, and phones but you either have to decrypt at the set top box/server or the client. If at the client you need a way to get the decryption key the client and write clients for each device. That'll either be a nightmare to maintain or to use depending on their priorities.