I still think Mogg is going to need to continue to be a superstar in Super Rugby right up until the squad is selected to be a chance at being the starting 15. His defence will be a major worry, particularly with the potential that he will be the last line defender against the likes of Tuilagi, Roberts, BOD, Visser, and North. For someone with questionable tackling ability, these are not the sort of players you'd want running at him in open space.
I think Mogg's best chance is to come off the bench. I find it highly unlikely that we'd pick a debutant at 15 for the first Lions test. I also think he is more likely to be a Wallaby winger than fullback (much like Joe Roff).
Deans will be stuffed either way. If Mogg isn't selected at 15, there will be outrage that a star Super Rugby player has been left out. If he is and struggles on debut, dropping high balls and getting steamrolled by massive Lions backs, Deans will be pilloried for throwing Mogg to the wolves in his first test.
As long as Barnes isn't 10, the Wallabies generally look better with him in the side than out of it. Providing he comes back from the hand injury and doesn't sustain another injury prior to the squad selection, I think he has enough games to prove his fitness and form and retain the 15 jersey.