I don't want to shortcut what we're doing with too much: but it's fairly clear that a handful of senior/important positions will need to be recruited around: Sakaia-Loto is a nice one for one with Phillip, but there's no question that we need at minimum 1, probably 2 Centers, a scrum half, and a hooker who can throw.
In terms of centers, I don't want a youngster: to be frank, we have absolutely sucked at developing centers, the players who've performed best in those roles for us (Hodgey aside) have been those who've had substantial super exposure elsewhere (Ellison, Inman, O'Connor, Harris, Meakes) That's not to say there haven't been failures there too (Sidey, Magnay etc.).
Most domestic centers look to be locked up unfortunately: Tamati Tua and Isaac Henry seem to be the only names of note currently uncontracted. Sam Johnson has been noted elsewhere: my left field pick would be Matt Proctor, who seems to be clubless at 30 after having been released by Northampton.