Does it matter for the trade whether Huberdeau and Weegar re-sign or not? I mean, obviously it matters to Calgary, but you do the trade with the information you have at the time. Right now, we really don't know.
Overall, I'd say Calgary definitely got more value, but that doesn't mean this can't be a win-win trade.
Calgary had to trade their young star. Ideally in that situation, you want another young star back (think Johansen for Jones). If that's not an option, then Calgary did the next best thing and got a real haul of assets back. Even if they won't re-sign, Huberdeau and Weegar are both UFAs on cheap contracts - Huberdeau at 50% retained at TDL carries a cap hit of just under 3m; Weegar at 50% is just under 1.7m; at TDL, that's practically nothing. One team won't give you three 1sts + additional prospects for Tkachuk (who even has that many assets?), but getting a 1st+prospect for Huberdeau and another for Weegar is absolutely realistic. Flip them both and you get a great jumpstart on your rebuild; turning Tkachuk into four pieces gives you a lot more flexibility and potential trade partners.
The problem is that Florida is not rebuilding; we're contending. Trading Huberdeau and Weegar together is not an option for most teams; separately, yes, but we need roster player(s) most of all. In a year, Weegar will demand more money than we can afford/are willing to give him. Letting him walk is lose him for nothing; TDL trade generally returns mostly picks and young prospects and is not a good option when contending. Huberdeau could have been re-signed, but not as a sign-and-trade, only in FLA, and he'll likely demand 10x8m, which is a lot for a guy about to turn 30. If you're not trading your players at the TDL, not signing them and not letting them walk for free, then what better option than an offseason trade this year?
Were there better trade options in terms of pure value? Possibly. Maybe you flip Huberdeau to one team, Weegar to another and get some mix of players/prospects/picks, which you keep as-is or use later to further adjust the roster... Or you overpay some on Tkachuk, get one of the best young players in the game who fits the team's needs like a glove, shake up the core and hope to acquire a D in FA/trade next offseason. But it's not like you can hit "pause" and wait if a better option comes up for Weegar and Huberdeau; 24 year old stars very rarely become available.
With Tkachuk, all of Florida's core is age 20-26, giving us a contending window of 6, maybe even 8 years provided we can sort out the D and that Lundell and Knight develop well. Time will tell how it turns out.