I think clearing out the "deadwood" especially the English lads isn't easy as they're on great money and they're not motivated to move as they're not going to be getting offers from top clubs we were very lucky that Everton wanted Rooney otherwise he'd still be knocking around. Utd seem to act with a bit of class when it comes to guys who've been there a while and haven't kicked up much of a fuss they won't force guys out. Those who say they want to leave might get frozen out like Depay & Schniederlin did for 6 months which is fair enough, Schweni was forced out but something clearly happened there in the dressing room in his first season that we don't know about. Reading between the lines senior players didn't think he was putting his body on the line for the team when they needed him as he didn't want to risk injury before the world cup.
Smalling, Jones & Young (who is injured) aren't exactly going to be top of teams lists to buy they're all on very good wages and they're probably all happy being squad players at Utd rather than starting for Southampton, West Brom, West Ham etc. I think generally all the top clubs are struggling to offload deadwood City got a load of guys out because contracts expired but Arsenal have guys like Gibbs, Debuchy, Jenkinson, Chambers, Wilshere, Joel Campbell etc still floating about.
I think one of Smalling or Jones will probably go before the end of the window but they can't both go until we know when Rojo is back as there's no way Mourinho will want to risk having to play Tuenzebe for a long period of time. I think the big team "deadwood" guys might find themselves either sold or loaned out very late in the transfer windows as teams start to panic as most of these players will only want to sign for other prem sides they're unlikely to go abroad and they're not going to drop down a league.
I don't think the form in pre season games will do anything to sway the managers decision making I'd be baffled if Lindelof didn't start the first game of the season assuming he's fit.