Regarding what to do with Rantanen, there are a few different questions.
1. Will he hit the open market?
Maybe. Players of his caliber usually don't but Colorado's cap situation is murky. If Landeskog retires or makes it known that he is not playing next year, his $7M cap hit will not be on the books for next season. If he plays this season or announces he will play next season, Colorado might not have to cap space to give Rantanen what he wants without moving other pieces. (In that case, I might inquire about Mittelstadt) The cap is going up but Makar is due for a raise after next year and they have a lot of money tied up with no goaltender under contract after this year. Take a look Colorado's cap structure on CapWages or something and see for yourself.
2. Would an 8 year $14M AAV contract for a 29 year old compromise the Blackhawks' salary structure going into their window?
I don't think so. Teams like Toronto and Edmonton, while flawed, have multiple players making 8 figures with term and the Blackhawks have none. They also have been hampered by the cap staying stagnant the past 5 years due to COVID. I think the cap might get to $100M by the time they have to pay Bedard and might even be $120M when they have to start giving significant contracts to other prospects in 4-5 years. Other than Jones, they really don't have too much money tied up long term to anyone and they will benefit from many of their prospects and draft picks playing on ELC's for the next 5 seasons I would guess.
3. Should the Blackhawks offer an 8 year $14M AAV contract to Mikko Rantanen?
I would say they should. Players like him don't hit the market much, if he even does, and he's still relatively young. I feel like when the Hawks signed Hossa, they had a feeling that he would age well. I have no idea if Rantanen will but KD should definitely do his due diligence on his profile and how 6'4 215lb 2 way wingers age. I also still think he's worth it even if he's not a 100 point player without MacKinnon. He's big, kills penalties (until this year for some reason), and can win a faceoff despite the fact that he plays on the wing.
4. Would Rantanen sign with the Blackhawks when other (better) teams will also be willing to give $14M with term?
I don't have a f***ing clue