There's always a long run.
This is but the first cup window if the GM plays his cards right. In three years, all of Hamilton, Tkachuk (safe assumption he gets a longterm contract), Monahan and Gaudreau will still have multiple years left on their contracts; all will still be in their primes. Brodie and Hamonic will be 30. Then there's still Jankowski, Bennett, and Ferland, all of whom would also be in their primes. Backlund would be but 31. That's a group of players that shouldn't be hard to build around.
Good management (aka good asset management) will open up another window when that first one closes. But bad management and short term thinking will close this window before it's even open. Like emptying the farm for two years of Duchene or Simmonds for example; the three year window becomes two with still no guarantees of anything.
Right now, I'd go as far as to say, the windows not even open even though the Flames don't have a first next year. Contending teams have four lines that can chip in and multiple high end threats. Flames have two of each at the moment. Adding a single big name won't fix the liability that is Gulutzan's love affair with fringe fourth line talent, or his questionable system. Flames need an abundance of quality depth and that's only going to come from within (i.e. Having Bennett, Jankowski, Dube, Mangiapane, Ruzicka, etc., pan out to become at the very least viable depth options at the NHL level).
The time is not now. Not unless Gulutzan magically stops acting like Brent Sutter anyway.