Both Dragonborn and Dawnguard were timed exclusives for the 360. They both came out months later for the PC and much later for the PS3.

I heard that the agreement between Bethesda and Microsoft was for two DLC’s to be exclusive for the 360 for a couple of months. Obviously Microsoft paid to have the exclusive rights.

Did the fact that Microsoft would no longer be paying for content mean an end to all Skyrim DLC?

The end of skyrim DLCs came as a result of BethGS moving their full team on to their next project.

Do you really think that's the only reason?

Yep.

Probably not.

They had all three DLC as exclusives. Not just Dawnguard and Dragonborn.