Harrison may come back, but I think of the situation as being more similar to Colvin than Bruschi. And even the effect of Bruschi's return has been greatly overstated. The issue is how soon he will be a top player, and be able to perform anywhere near past levels. After all, Colvin took a couple of years, and even now nowhere near his former self (would you sign him up for $5M a year?). Personally, I expect Harrison to be on PUP, come back at mid-season, and be part of a 3-man safety rotation.