It's not Paquette and Brown replacing Cally and Flip it's Kucherov and Johnson. That they are earning bigger paydays sooner or larger than we anticipated isn't a bad thing. It's natural for teams to evolve. Our evolution is coming from success.
Johnson replaced Filppula two seasons ago. That Johnson was paid like a third liner meant it was affordable to keep Flip. Even if we were still able to afford a $5M 3rd line center, Namestnikov is ready to assume that role and paid accordingly. Filppula's cap space fits raises to Johnson and Palat into the budget. If we need to lose one of those three it's Filppula, AINEC! Sure it hurts depth, takes some of the insurance versus injury, lessens overall leadership and experience, hurts on faceoffs, etc. But, it is only a necessity because we have better players already outplaying him and it is almost time to see them get paid.
As for Callahan, Kucherov replaced him. Kucherov is going to become a $6 Million dollar man (or thereabouts). He deserves it, he's earning it, and it's a very good thing. Comparatively, Kucherov has been more significantly underpaid for his production to date than Callahan has been overpaid for his. I get that they play incomparable styles, that Callahan brings elements valuable to the team that Kucherov can't and won't. Still, ask any Lightning fan who they would rather have if forced to retain only one and we're all keeping Kucherov (except maybe you, Thunder Buddy). Callahan might still survive Kucherov's new contract. Yzerman and/or Cooper may view him as an integral piece. Callahan has leverage with his NMC. Contract undesirable in trade or buyout. Whatever. Callahan will be moved before not moving him costs us Kucherov (or Drouin).
Stamkos, Johnson, Kucherov, Palat, Drouin, Killorn,
Hedman
Vasilevski
That is probably what we're building around beyond NEXT offseason. Definitive "core". Still plenty of cap space to build around that. Plenty of talent in the organization to fill the majority of holes, including the vets on bigger deals currently. Yzerman has options. Things can and will change, but, there is nothing to panic about. Players come and go and life goes on.
Bishop, Stralman, Callahan, Filppula, Garrison, Coburn, and Boyle all contribute. They're all important to the current team's success. All pretty fairly paid. All of them entirely expendable if needed for cap space between now and when Cally's contract expires. I worry about our defensive depth not having replacements for the likes of Stralman, Garrison, Coburn; or not being able to afford the likes of Koekoek or Sustr more than I worry that we don't have adequate replacements for Flip or Cally.