Yes, he's exhausted his prospect eligibility, but he's a player we've followed here for years and was a part of the Mariners rebuilding plan, so we'll still talk about him. As the incumbent second baseman, he's the one most obviously out of a job. He could probably play elsewhere on the field (he was a shortstop in the minors before sliding over), but the most likely scenario is that he wears a different uniform next spring.
While that would be unfortunate for most players, it may be a good thing for Franklin. As a left-handed hitter with moderate power (below average by major league standards but above-average for a second baesman), Safeco Field was a terrible fit for him. As you can see by his spray chart below, almost all of his power was to the pull side. Safeco Park is not friendly to left-handed hitters, and there were at least three fly ball outs that Franklin hit that would have been a home run at many other parks.
Franklin could see a solid boost in his power numbers if he can get out of Safeco. He hit 12 home runs in 102 games, for a 19-homer pace. Getting out of Safeco and into a more hitter-friendly park coupled with no longer being rookie should put him in the 20-25 home run range. You can't expect a hundred point jump in batting average, but Franklin also shouldn't be a .225 hitter over the course of his career. Put all these minor improvements together and you have a nice little second baseman.
As of now, Franklin is still a Mariner, and there's a chance they could hold on to him and turn him into a utility player. More likely, however, is that in the Mariners continued effort to go for it this season, they flip Franklin to a team for whom he has more value. Franklin's days as an everyday second baseman are over, but the Cano signing probably increases the odds that he makes it as an everyday player at all.