I reckon we need just four more top drawer players who are fast, and are still young and hungry enough to improve further.
If we can sign Icardi for CF, Xhaka for the CM, Gotze for the wing, and a LB who knows how to attack AND defend well, we will be in a very good position to push on for the premiership next season together with what we already have.
As for the strikers, there's no need to decide who is no.2 or no.3 - let them all compete for the right to play. With the inevitable suspensions and injuries, we will need to have depth if we are to compete well in several competitions (I am presuming we qualify for at least the Europa League).