Ottawa gets a center/winger making less than the AAV they wish they could extend Pinto for. Calgary gets another right shot forward (they're short on right shots) and extends Pinto for more than Ottawa is willing to pay. Say 3 years at 2.75-3.0 mil/year.

Problem is they’d still need to move out one of Joseph, Kubalik or Brannstrom to fit Dube in

How does a trade that puts Ottawa over the cap solve their cap problem?

It doesn't solve their cap problem, it solves their Pinto problem. They want to sign him for 2.5 million or less but he won't sign for that.

To make this really work for OTT, I think a 3rd team needs brought in for OTT to be able to dump some cap to get Dube to fit in their cap structure. So maybe CGY throws a mid round pick in to that 3rd team to help facilitate the trade. It would be worth it for CGY as they get the player worth the highest potential, and possible replacement for Lindholm if they can't get an extension done

That likely only works if Tarasenko is one year and done in OTT. Dube’s currently produces more offence, is more reliable and better defensively than Pinto, so he’ll be looking for $4+mil/yr on his next contract commencing next season

That is a great point! I wasn't sure what to think of Tarasenko's one year deal anyway, but you're right, price point wise this only makes sense this way, unless with the cap rising that might be enough (with other moves possible over the summer) to make it all work long term