It's really easy to say that now with the benefit of his recovery but keep in mind Stamkos had plenty of question marks, too, including a season of his own that made people question him the way some here questioned Kopitar, on top of the injuries, and in addition there's still a fair question of whether he can produce on his own after riding shotgun with superstars on his wing throughout his career (St. louis, now Kucherov, with his down years coming in between).
Beyond that 1.5 million dollars isn't the difference in 'broken' vs. 'not broken' so I feel like you're making a mountain out of a molehill with the difference between their contracts but even so there are already a ton of players making more than Kopitar. This is similar to when people freaked out about Doughty making SEVEN MILLION?!?!?! only for it to end up a middle of the road contract for a top-pairing d-man. In several years, 2C Kopitar making 10 million won't be the reason this roster isn't competitive. We're already getting there now, where 10m is the middle of the road for a cup winning 1C. As recently as last year it was fair value, this year it looks like garbage, I'm willing to bet reality--next year--is somewhere in the middle and that Kopitar isn't dead.
WRT to roster construction because I think that's your bigger point--K17 has long been asking for us to integrate cheap skilled youth. Well, now's the time. And by the time they're ready to be paid, we'll be fine on cap space. I just don't see the imminent destruction in 2023 that you're seeing, there are too many scenarios and too many moving parts to say anything like that definitively unless you're counting on Kopitar becoming a 40 point shell and the cap shrinking.