I think the need for Ekholm is a bit overstated. Yes, he's great and a perfect fit for Bouchard and was an incredible mentor for him as he came up. This year was a bit of a step back for Bouch, but I'm confident he uses it to motivate himself to be better next year (unless we win the cup, in which case he can have a summer off and get fat for all I care). I think Bouchard becomes a consistent, elite defender able to carry a pair as long as his partner is reliable.
Our team is deeper and more experienced now than when we aquired Ek, or even compared to start of the season. I think Nurse could be a guy who has a better 30's than he did his late 20's. He still has all the physical tools, and I can see all this experience finally sinking in and him having some of his most reliable years. A guy like Pietrangelo had his highest Norris finish at 30, and most productive season at 33 for example.
Then there is Walman, who is money. More experience on a winning team, with older guys who can mentor him a bit can only beneficial compared to being the lone guy on SJ, or a part of whatever Detroit's "defense" was.
I think we have the pieces to replace current Ekholm by committee, and he will still be piece of the puzzle for a few years here. Just maybe not enough gas in the tank to do it for 22+ mins a night.