I would be very surprised if Aiken doesn't make the 53 and isn't a weekly active. The competition for the final WR/ST slots is going to be tight, but make no mistake, these are special teams roster spots first, backup reciever spots only in emergency situations. Out of the group of Aiken, Edelman, Nunn, Slater and Ventrone, Aiken is clearly the "star" in a special teams role. Granted, others may provide more long-term upside, but upside isn't worth much when you're giving up 20 yards on punt returns.
My best guess: Aiken and Edelman make the team as WR/ST players. Aiken wins his spot on special teams merit. Edelman wins his spot with a combination of upside, ability to simulate the wildcat back on the scout team offense, and ability to be the emergency 3rd QB on game day.
This leaves Slater and Ventrone in a battle with Alexander, McGowan, Ciruciru for probably one more special teams slot.