Wallner may force his way back (good for him!) and the options are for him to replace Martin, Farmer or Margot. Martin can be optioned and his role is as a platoon OF and possible Buxton replacement. Margot can fill that role as well. Farmer is reduced to platoon second baseman, but an injury would give him reps in the infield. Margot is a platoon OF, has a couple starts in center field and a few starts against right handed pitching, including in the nightcap of the day/night DH on Sunday. There would be arguments to keep any of the three and losing Margot or Farmer would mean they wouldn't be in the organization any longer.
I like what Martin brings to the table, but his performance as an outfielder has been spotty, at best. It looks like he has the skills to be more than adequate, but he's misplayed a lot of balls. Farmer and Margot have limited, at best, trade value. The Dodgers might give something for his services, but more likely would just pay the rest of his contract. I don't think any team regards Farmer as a potential regular shortstop.