Quoting: DirtyDangles
Again, why would Carlson want his "new team" to give up assets for him when he can just go there for free?
You're assuming he's going to a team he's a fan of in order to help them. That's best case for any team, sure. Best case for the Capitals is that he signs an extension right away and fans stop wondering.
Worst case for any team ending up with him is that his agent sits him down, points out this is the last big contract of his life, and will determine whether he retires with 40M or 70M in the bank, he sees some significant difference between the two (I can't imagine it, but I guess there are people for whom 1M isn't "wealthy" anymore, so who the heck knows?) and he pushes for 8.7x8, or more, with any team that will give it to him. That would then put leverage in the Caps' court, because several teams would be improved by adding Carlson, even at a ridiculous cap hit, and only Washington is allowed to ink that deal.
If a team has to trade a young player and a 1st round pick to get the defenseman who scored the most points through this regular season and the playoffs, they might. If Pulock is untradeable, fine. Whatever. I think NYI's #1 center next year is Barzaal, and they would be greatly improved if they traded Tavares for Carlson, but I don't think they're smart enough to get it done, or that Tavares would be willing to fit his salary into the Caps' budget.
The secretly fine replacement for John Carlson's offense is to put the superexpensive UFA right defenseman they signed four years ago on the power play: Matt Niskanen. He's never had a full season of top power play time, but has topped forty points a couple times. Let him get to know the offense and he'll get 50, easily. Sign Luke Schenn or somebody defensively solid to play third pair and replace Carlson's defense. Trading Carlson for Tavares and letting Niskanen and Bowey compete for power play time leaves the Capitals just as good, which, today at least, seems okay.
The other fine replacement is to sign a former Capital who owns a house in DC, plays the same position, and is the only active defenseman to post a 30 goal season: Mike Green. He's not as good defensively as Carlson, and had fewer points this year, but he's almost as good, and if you put him back with Ovechkin and Backstrom, he could put up some good numbers. So trading Carlson for Tavares and signing Green makes the Capitals better, overall.
The trouble with making the finals is that all the Caps' free agents will get offers, and Washington may have to decide whether to match a big offer to Carlson, or to give big raises and long term to a whole list of guys who stepped up: Kempny, Smith-Pelly, Beagle, and Wilson. If they decide the latter four represent more continuity and improvement than Carlson, they need a defensive, minute-eating right defenseman to replace Carlson's defense. Niskanen and Bowey can put up some points.