The striker and midfielder are obvious needs, so pretty straightforward there. Take your pick of god knows how many options.
Goalkeeper is the more interesting one, because having made do with loan signings for our back-up goalkeeper this year we will need to make a signing regardless of what we do with De Gea. So do we just sign another back-up? Sign genuine competition to compete with him? Let him leave and sign a replacement, presumably then also having to sign a second goalkeeper for back up? With him not having singed a new contract yet the options are quite open-ended.