I think Kevin Falk plays a nice role for the Patriots, but the chances of adding a back who is younger, more durable, possibly faster is worth looking into. Yes, Kevin can break the occasional punt return, but his fumbles have been devastating (Pittsburgh 2 years ago and Denver last year)...he may be far from done, but he is also far from being the perfect scat back (Dave Megget set that standard).
I'd love to see him stick around, but would like his replacement waiting in close proximity.