It'll probably never happen with out of production models -- the licensing fees for Thunderbolt meant most manufacturers didn't pay them - including on your system.
Yes, Intel/Apple is removing that obstacle this year -- but it's unlikely to affect existing systems.
Thunderbolt devices will likely work - for the most part - with your system, but the fact that it was built without Dell having paid the licensing fee, and that the system is out of production now - means that official support is unlikely to ever come for it.
