We've needed to cull the squad for a few years now. Personally, I think it was too large and unbalanced even when we were in European competition, so with Champions League being a non-entity next season, it's vital we orchestrate a mass turnover this season if any. Of all the players you've stated, I'd be happy to see nearly all of them.
Three players have already left, so ideally, we'd be looking at around ten departures by the start of the new season.
Javier Hernandez - I just don't see him getting a fair amount of gametime given his quality. If he was omitted from the side on a regular basis under the Sir Alex and Moyes' reigns, he's going to find it even more difficult to feature in the first eleven in a system which centres around just the one striker. From the clubs perspective and the players, this is the right move for both parties. We could receive a decent fee for a players who might not see his market value rise above what it currently leaves, while also having one less striker to restrict both Welbeck and Wilson's development; and Hernandez could move to an established and decent club, playing on a regular basis.
Anderson - Should be the first out of the door on that list. While quite a few of those players you've listed, will be subjective whether we should sell or not, I think Anderson going is pretty much a unanimous verdict among all United fans. He's never going to have a future here whoever the manager is, so we should look to cut our losses as soon as possible. I foresee a return to his native country, as many failed Brazilian footballers in Europe tend to do.
Luis Nani - Like Anderson, I do think it's time the club and player part ways. He's had seven seasons here and while it is unquestionable that he harbours ability, his tenure has been inconsistent to say the least. Add recent injury issues over the past few years and I don't see him really excelling again - even under a coach like van Gaal. We'll probably receive a decent fee for him, so like Hernandez, now could be the ideal time to cash in.
Ashley Young - Just simply one of the worst players in our first team squad. A player simply out of his depth at this stage and not even a player he can perform in a squad role capacity in my opinion. Obviously it'll be difficult to sell given his extortionate wages, but alas, QPR have returned to the Premier League, so there's a potential suitor.
Alex Buttner - Probably the player who is most in jeorpady of losing his position at the club with Evra's contract extension and our concrete pursuit of Shaw. Plays like a converted winger and isn't good enough to challenge the first choice left back and keep competition high. Even Dutch compatriot van Gaal couldn't offer assurances over his future.
Bebe - Self-explanatory.
Ben Amos - Lindegaard is a more than capable deputy for de Gea and Johnstone and obviously Milinkovic have more scope for improvement.
Darren Fletcher - Probably the most difficult choice in deciding who should go out of himself, Fellaini and Cleverley. Looking at it front LVG's perspective, I doubt he'll be sentimental in his approach to which midfielder should stay and go, regardless of their status at the club and what they've been through. He may be of the opinion that there's a role for Cleverley and Fellaini in his system. The former doesn't have any exceptional traits, but he is a tidy player who can and has proven to thrive with constant movement around him due to his ability to retain and circulate possession even if he is non-effective in the final third. For Fellaini, I doubt he would operate as the pivot if LVG does opt for the 4-3-3, but he might play as a box-to-box like he does for Belguim. Maybe more than just the one of those three will leave, but I think it might be difficult to offload more than one; Cleverley has an admirer in Martinez and Fellaini is a well-established international who is seemingly available. I actually think LVG will favour Cleverley over the other two however, despite having a worse season than those two.
If these players are to depart along with Rio, Giggs and Vidic, we've lost invaluable experience in some areas, but more importantly we've significantly trimmed the excess fat in the squad. With the right four or five additions we'd have a competitive and healthy, refined squad. That's a better basis for LVG to work with especially when you factor in our exclusion from European football.