Now that Bethesda has no more plans on making any new DLC for Skyrim, I really think that they should take a look at the big mods out there that may have DLC quality and sponsor them, support them, or at least give them the Bethesda seal of approval. There are several mods out there that are made by either 1 person with help from friends, and others that are made from groups of people that have a common goal. These kinds of mods are so big that it must take them so much time, so they need a lot of support, and even a seal of approval from the company who made the game they are modding for would do a lot to help, not only to get the word out, but also may bring in more modders to the projects.

The ones that I can think about are:

Wyrmtooth (already on the Skyrim Nexus and on Steam
Silgrad Tower, From the Ashes (in development)
Rangers of the Red, Journey to Valenwood, (also in development)

I am sure there are more out there that I haven't discovered yet.
The only requirement that I see for a mod to get that kind of support and/or official recognition is that it stay within the lore already setup.

If Bethesda does this, i think that these types of mods for Skyrim will really take off.

Bethesda doesn't play favorites, which I endorse 100%. This would completely change the base of our community and people would start modding for fame and Bethesda's approval, instead of just for fun like it should be.

Not to mention we all have different standards for mods. Very VERY few actually reach professional, well rounded levels of quality. Your wonderful golden perfect mod might look terrible to me, and visa versa. This would do nothing more than create a lot of controversy and conflict in the community, and they would never do it.