Meh. Walker was OK, but didn't offer anything Wilfork, Branch or Siliga do, so he really wasn't all that necessary. Even if one of them goes down, the other two can pick up the slack without it being overly taxing with so few games remaining and a bye ahead.
Easley's skill set is completely different, and not so readily approximated by anyone else, so it could just be a matter of crossing their fingers and hoping rather than an expectation.
The Patriots had no need for Walker, and took a chance that he wouldn't be stolen which was true for several weeks. Even now, it is possible that they could have promoted Walker instead of letting him go.
Not seeing it as a meaningful loss, either as a player or an indication on anyone else.