Van Gaal is definitely the sort of manager who will have no qualms about having Shaw and James as his options at LB (or LWB or whatever) going into the season if their performances continue to improve. His comments about a 16-year-old Seedorf when he was asked about experience in his first presser with us confirm the evidence from his career that he basically ignores a player's age and experience and judges them purely on their performances.
So where some on here might say 'Shaw and James both look decent, but we can't risk relying on two such inexperienced players when it comes to the season proper', Van Gaal will, I expect, just think 'Shaw and James have been good... so they can be my LBs.'
I hope so, anyway. It's what he's always done in the past.