With the Packers having drafted Spriggs and Murphy I highly doubt that Barclay will make the final roster.
Besides that being a side note to the main point, whether Barkley will or won't was not being argued.
The point was that however small the possibility of Rotheram being considered for the roster, Barclay still needs to be considered as a competitive option.
While conventional wisdom has 9 OL spots already filled, a heavy number that is reasonable giving the impending free agent class, you might consider why, perhaps, Barclay is still around. Here are a few possibilities:
1) An OG spot may open up due to injury before final cut downs, with Barclay perhaps percieved as a more appealing option than Rotheram for 2016.
Theoretically, he can back up at RT as well. Sometimes guys take a second season before showing they're over an ACL. In fact, if the Packers are confident he's returned to the level of play when he took over for Bulaga pre-injury, he'd have to be given consideration if Murphy does not work out (see comment below). I'm sure the Packers would want to see if that's the case particularly with no other likely candidate for the RT backup spot other than rookies. Spriggs has to focus on polishing his LT skills since he'll be expected to be ready to start there in 2017. That leaves Murphy or Barclay.
2) Murphy could turn out not to be all that. Since when do Packer 6th. round picks live up to the abundant post draft optimism? He wouldn't be the first 6th. round pick to end up on the practice squad, Ringo being one example. The guy has work to do. Maybe more than you think.
3) To reiterate, of all the possible trade rumors that could be floated, the one that makes the most sense would be Tretter, assuming confidence is gained in Rotheram as a backup C. Rarely do you see as wide a spread between what a player is worth to the Packers vs. his value to somebody else than you see with Tretter. Such a trade would argue for Rotheram over Barclay, which takes us back to points 1) and 2) as possibilities for him.
It would be foolish to actually predict a specific trade, but if one was inclined to speculate about one in particular at this juncture, trading Tretter would it.