That's not exactly set in stone. I'm still hoping Ronnie is off before the window closes. That would leave us with Martial up front and Rashford as backup, quite thin but manageable if the other players are contributing well, which you'd expect once they get up to speed with ETH's methods. Let's say we buy Antony, then him and Sancho cover the right, with Rashford and Sancho covering the left, but Rashford might also be needed up front. Instead of buying both Gapko and Antony, I'd roll with Antony and properly promote Garnacho.
We simply have to secure his long-term future here and ETH is not the type to ignore an obvious talent due to a young age, on the contrary.
