That's an good question as we have to comply with the PL's version of FFP which limits wage increases.
The main way of accommodating the newcomers is if there's as many going out as coming in. That's can be hit and miss depending on who we can actually shift but I'd guess that's where the bulk of the savings we need will come from.
So I'd assume Yaya's wage would be one of those we'd be most keen to shift, which alone could possibly cover three newcomers. And it's funny that from saying he can't wait to go, he's now saying the opposite. I suspect that's a negotiating ploy to get as advantageous an exit as possible. But one would assume that as we can only have a squad of a certain size, it'll be one in and one out. So if we get say Gundogan and Pogba, then it'll be Yaya & Fernando making way for them. A new left back would see Kolarov out. Stones/Laporte would replace Mangala. Etc.
Additional ticket revenue could cover someone like Pogba's wages but it hardens my suspicion that we've got some big commercial deals lined up