If Risto is a franchise defenseman, and Kulikov and McCabe are legit top-4 guys, the only thing we're really missing is a second RHD to play in the top-4. Not easy to come by, but not as hard to come by as a true #2. I think it's a perfectly viable long term to have a cornerstone #1 and then go committee-style top-4 with the rest. Toss in Guhle covering bottom pair LHD minutes while Kulikov plays out his hypothetical extension...all told McCabe's play has made me reasonably optimistic about the blue line long term. Just have to flip Bogosian into something better.
Don't forget his 20 games of suck upon returning for injury! Honestly though, even if he plays the rest of the year, so you have any confidence whatsoever he'd survive a deep playoff run?
And that's without getting into whether he's good enough when healthy anyway...