Yes, I think Quinn will be okay, and KIngery, brief as it has been, might be a revelation. But the difference between Kingery and Williams is they have found playing time for Kingery. My guess is still that Williams will be included in a July trade, and they will bring in a more experienced 4th OF. Professional pinch-hitters are few and far between, it's a tough job, but someone who can more easily play that Matt Stairs-type role is probably in order.
With so little playing time available Cozens or Walding really could just as easily be the LH PH, they are obviously not as good as Williams and being a bench player always means small samples, but if the only thing that is going to get him untracked is more ABs he's not going to get untracked.
Altherr hasn't had much of a chance either but he's ultimately making it easier for them to release him, they really have no choice if and when the moment comes.
Not sure if Williams is playing tonight, latest article I read said during the Marlins series. But given the recent results (for both the team and Quinn) maybe a change is in order.