Odin is an entirely optional boss fight, not a required one. They're probably not gonna give us an Odin-themed summon. The only reason we got Phoenix is because its appearance was part of a major world changing event in the MSQ.

Even if we did get Odin, I don't think we'd be riding around on Sleipnir or using Gungnir. Summoners are mages, not warriors. We wield books for a living. Spears and swords are out of the question. If we did get Odin, the more logical option would be for us to use non-elemental spells with high damage output and a stacking debuff or something.

At least that's what I think.