As a Flames fan...no. That is a huge price to pay for nothing.

I don't see it as "nothing".

Combined Dzingel & Ferland could add 40+ goals to the line-up. Currently they're combined 31 goals half way through this season.
Ferland under Peters I think will understand what his role is far more clearly than in the past, and that is to be a "presence" on the ice, while chipping in with goals every few games. (or more) Ferland could also take some physical pressure off guys like Tkachuk & Bennett. He's got enough skill to become a true power forward.
Dzingel can play any forward position and can move into any slot required.

This also allows for summertime decisions to be made on guys like Frolik.
I appreciate if you don't fully agree, but I think this would be a positive going forward

The issue with this is the Flames are giving up 3 of their top prospects in Mang, Dube, and Kylington, as well as their 1st round pick when their cupboard is already pretty bare AND their 2nd. This basically cleans it out completely, to add a few rental players. They can't afford to re-sign Ferland who will likely get 5-6M in the open market. Dzingle is also a UFA who will be due for a larger raise. This is just too much for the Flames to pay for rentals.

I'm not against the flames dealing a 1st round pick, or a 2nd round pick, but it would have to be for a player with some term, who is on a friendly deal. If the Flames are moving a 1st round pick, the only players they likely do this for are Stone, Duchene, Panarin, etc.