Darling is good but at 4.15M, I don't know that he was the answer. If things don't work out this year, you can trade Crawford and roll with Forsberg/Berube next year for a combined 1.45M. I love Crow, always have, always will, but if things aren't working out for the team, just pull the trigger and move him. 4.55M in cap space, not to mention Panarin's bonus money. We could have 8M in extra money to play with. Crawford should be the last goalie to make 4M+ of the Toews/Kane era.
Eh... a couple major problems with that. First, Crow has been insanely reliable for us since he's worn the Indian Head other than occasional fluctuations that happens to all goalies (especially this past year, where he was having a career year before the appendicitis). The idea of moving from a known and reliable quantity at a time when we probably have more question marks on our blue line than at any point in recent memory seems like a recipe for disaster. And that's especially the case as Forsberg and Berube are massively unknown quantities for us. That'd be a Canuck level move to go from reliable starters and backups to giving the franchise over to just potential nobodies.
Second, regarding the salaries, for next season Crow is basically what you'd expect the starter for a contender to make (he will be tied with Schneider as the 7th highest paid goalie in the league, and four more goalies are making within a mere quarter million less than Crow) while Darling is near the bottom as starters at the 23rd highest paid goalie.
http://www.spotrac.com/nhl/rankings/cap-hit/goaltender/
The rate for starters is established, so if you expect to stay below $4 million going forward past Crow, you're essentially stating you want a revolving door of goalies coming in and out every couple of years or settling on fairly low quality guys. Neither are good for our chances if you ask me.
As for the cap savings, those would be temporary at best and likely not in their full amount as well. It is very difficult to move a goalie making a decent amount of money with term, as flat out the demand isn't very high. Contenders either usually have a guy already or are stretched cap-wise as well, and non-contenders wouldn't be interesting in paying for a goalie when they have holes all over the place already. That leaves a limited number of teams somewhere in the middle that believe a reliable starter could put them over the edge, and at that point they have a good bargaining position as they know you're doing it for a cap dump as well. Trading Crow,or any other starting goalie, would almost assuredly involve eating some of that salary or trading a player, prospect, or a pick in the process as well.
It's far easier and more reliable to stick with the guy you know and can trust and trade the backup than vice versa.