JMO, naturally, but I think the bolded part is you answering your own question. Keeping 5 should be easy. For the sake of keeping a 'big body' in, I'll put the young guys in this order: Silaga, Armstead, Jones, Vellano*:
Wilfork
Kelly
Williams
Easley
Silaga
Armstead**
Jones**
Vellano
Then it just becomes a matter of how many you can carry, unless you're willing to risk Armstead on a practice squad move. You'd have at least Easley/Silaga around if you carry 5, though, so youth would still be served. PUP possibilities (Wilfork/Kelly) and suspension (Browner) lead to the possibility of carrying more to start the season, while the seemingly likely extra QB undercuts that a bit.
*I'm just making the order to make an order and to keep some beef in the younger group. I'm not necessarily assuming that this is how the team currently has them slotted.
** Part of the question for these players, I think, boils down to just how much change the Patriots are planning with their DT style. Those two players are a lot more likely to make the team if BB is going to go whole hog with a 1 gap attacking style at DT than they are if BB is still going to look at DT as a stop first, attack later defensive position.