It looks like Sharks will trust youngsters for the start of the season, but if they struggle or Sharks stay at playoff position, I can see Doug Wilson making trade for top 6 forward (especially RW is weak).
Frolík is ideal candidate, great two-way player, can score and play hard. I think if he gets 15+ minutes on Sharks 2nd line, he can have 50+ points if he stays healthy whole season. His health is question as well as his play-off performances.
Problems are that Sharks and Calgary are divison rivals (I expect them to fight for the first place in divison), Sharks don´t have cap space and maybe even players/picks to make Calgary accept the trade. Plus he is just one season solution, I don´t think Sharks would offer him new contract (maybe his last big contract).
The value depends on the time of the season and Flames results, but in general, I can imagine trade similar to Vesey, Shaw or Burakovsky, so 2nd/3rd pick + prospect, something like this (according to many posts, Calgary fans want to move him to make space for Tkachuk - well this could help).