That was then though with F3. The consoles atm have the "add-ons" menu in the game, so it would be relatively easy for the Beth to implement a strict load order system, with the add-on menu. I would like to read for myself Beth stating they cant patch DLC for Skyrim, because I havent seen them say that for this title.
Essentially what Im thinking is a simple DLC-Update.esm that is always loaded last.
To be honest, Bethesda could do something like this. So that "Dawnguard-Update.esm" always gets downloaded, but a kind of "if Dawnguard.esm exists, enable the update, else don't enable it". So DLC users get the update, non DLC users still get the update, but it's just not enabled. No crashes for either, as ESMs can overwrite ESMs since F3.
That way even if Microsoft don't support content specific patches, Bethesda can still deliver them.