Ellis is an interesting option; his .398 wOBA in 2008 (at AAA) was impressive, even coupled with a little BABIP luck. I would suggest that it is possible, however unlikely, that he could outhit Martin.
Some how, some way, Ausmus is still projected to be useful, even if it is hilarious CHONE projects him to get 319 PA.
To be fair to Ausmus, congrats to him, only 393 players in history have gotten at least 7,000 PA. Sure he has the same wRC+ as Royce Clayton, but that’s still a perfectly good career. And FWIW, baseball prospectus rates him as an excellent catcher.
I think, if I am the Dodgers, that this is the perfect time to play Ellis and hope he plays well. If he does, and Martin looks healthy, then it’s possible to trade him (of course if you think Ausmus is a good enough backup).