I've been very dismissive of the idea that somehow we would move Steen this offseason as part of a cap clearing project to re-sign Petro, but I may have stumbled across a way to get it done that is a win for everyone involved. I still see no way that Steen doesn't finish his career here (and I expect that next season may be his last) but maybe this will work.
Trade Steen and our 2021 1st to Ottawa for the SJS or CBJ 2021 2nd round pick that they hold. Ottawa buys Steen out, as that is the only condition (in this scenario) under which he agrees to waive his NTC. Blues then sign Steen as a UFA for a little more than the actual salary he lost to the buyout. What is the impact?
Draft wise, we're probably giving up 20-30 slots in the draft, which seems a small price to pay to retain Petro.
Cap wise, we save roughly $4.25M based on his current $5.75M cap hit, assuming that he is re-signed for roughly $1.5M after the buyout, and since it is an over-35 contract they can even include some incentives. Steen pockets $2,333,333 from Ottawa, which means that he makes $3,833,333 in actual guaranteed salary next season or $333,333 more than he would have had he played out his contract. Ottawa picks up $3,416,667 towards the cap floor for next season and $1,166,667 the following season despite only paying out $2,333,333 in total. They also move up 20-30 slots in the draft. It makes great sense for both teams in my view, I just don't know if the trade/buyout/re-sign element of the deal passes muster with the changes they just made to the CBA. Combine this with a trade of Allen where we retain $1M or less and you've freed up $6.85M-$7.85M in cap space for next season, assuming you replace Allen with Husso.
This path would also work using the Bozak contract, but Ottawa spends $500K more in that version and gets $1M less in cap hits over the next two years, and the Blues probably have to spend as much ($1.5M) or more on his new contract to get him to agree to the deal, meaning the cap savings is probably only $3.5M or less. This version, on this basis, is much less financially efficient for both teams.
The "long-ball" play here is to make the trade/buyout/re-sign deal with Steen and trade both Allen and Bozak, replacing Bozak on the roster with Kyrou, freeing up around $10M-$12M for maximum flexibility. Once you have Petro and Dunn locked up, you might have enough money left to go out and get someone like Haula or Soderberg to fill the Bozak slot for far less than his $5M.