He can help with the transition to Wade's D for the other LB's, of course, as has been mentioned.
But I think Barwin can still play his natural position at a very high level. Maybe not quite Pro Bowl level, but certainly playoff enhancing level. This first year for the new regime makes him invaluable. A real fine signing by a smart FO and coaching staff, imo.
If he has a statement year this season, as I expect, then I could see a reasonably priced extension of 2-3 more years for him as a Ram. Can't have too many high character leadership types that can consistently make plays on your team. Both McVay and Wade know this very well and I suspect that they dangled that extension carrot in front of Barwin when they were wooing him as a potential FA.