I had a long thing typed out, but I lost it. Basically, I have been thinking, and an Altmer Dragonborn makes a ton of sense to me. This idea rests on two pillars of thought. Bear with me and kindly ignore the fact that there is a Nord Dragonborn behind this post.
1: The Dual Nature of Akatosh/Auri-El and the Human Fall from Glory
Essentially, the human emperors failed to maintain the barrier between Oblivion and Nirn, requiring the direct intervention of Akatosh/Auri-El to permanently restore the barrier (see: Oblviion). Akatosh/Auri-El has since removed his favor from humanity, and, as evidenced by the clear rise of the elves since Oblivion, returned his favor to mer. As the original instituting authority of the initial elven empires, Akatosh/Auri-El has propped up the elves before. This is also likely a possibility because of the schizophrenic nature of Akatosh/Auri-El, and recent events in the TES universe could very well explain be explained by the predominance of an Auri-El centric identity. This shift from propping up human authority to establishing mer authority after the failure of the Empire to maintain the barrier without divine intervention is the first pillar.
2: The Inadequacy of Thalmor Means and the Realization of a mer Tiber Septim
Auri-El, per Elven lore, regrets creating Nirn and essentially trapping lesser Aedric spirits there (mer). He very much wishes to aid mortals in achieving transcendence to Aetherius. He does not, however, support the plan of the Thalmor, which involves interfering directly in his realm (time). Therefore, he initiates an alternate plan: the creation of a new divine, an elven Tiber Septim, if you will. Given the state of disrepair and disuse the Chantry of Auri-El is in, Auri-El can no longer guide mortals to transcendence through it. By creating a tenth divine charged with guiding mortal kind to transcendence who has the power to do so, however, Auri-El may establish a means of freeing the lesser Aedra that is not as susceptible as the chantry to the machinations of mortals. The ultimate goal of helping the elves and mortals in general transcend his regrettable creation is the second pillar.
There are other connections in my head, such as the Dawnguard storyline signalling a shift of focus towards Auri-El, but these are the two big ones. Thoughts?