If DeBrincat, at 24, didn't fit with any conceivable rebuild window, how long will CHI's rebuild be? 10 years, 15 years, half a decade?
Even if it was 5 years before CH became more of a contending team, a 29, 30, 31, 32 and 33 year old DeBrincat could have been a valuable part of a winning roster for 5 years.
Also, you can't expect to return to being a contender in a reasonable time frame if you get rid of your most valuable players that are still 25 or under.
"Debrincat didn’t fit with any conceivable rebuild window - those three years make a big difference, especially considering the UFA hurdle at 26/27."
Unless you know that there was no headway to make with a long term contract, this UFA hurdle at 26/27 is irrelevant since you would be using the remaining RFA years to help lower the Cap hit over tome on a long term, 8-year contract, ideally.
DeBrincat was a proven scorer as a two-time 41G-scorer and one-time 32G-scorer in 5 years played. He also scored 28 goals (in his first season) and had an off year at 18Gs two years ago.
You don't get rid of such a player nonchalantly.