Maybe. Toffoli is also 2 months away from turning 30, and not realistically a player we could or should extend in 2 years when his contract is up as he's not a particularly fast skater now and it's only going to diminish with age. He's likely to be better but it's not out the question that Heineman or the combination of Heineman and the prospect we take with the 1st are more valuable in 3-4 years.
I also don't think the fact that the previous regime failed drafting in the 1st round is a reason to just be a complete doomer about the very concept of trading veterans for futures. The last time we traded a vet for a 1st + a prospect it was Rivet for Gorges and Pacioretty, I realize that's cherry-picking a good outcome but it's not like this never ever works out for anyone. Perhaps they could have traded him for younger roster players or more developed prospects instead, but it's also possible that there wasn't really a deal out there for that kind of player and we'll see that sort of trade for Dvorak/Chiarot/Petry/Gallagher etc. Trading the player also opens up cap to sign players in the future. It's not like that roster spot is just going to be a blank void now until the 1st round pick does or doesn't develop.
It doesn't really matter whether we trade them or not, players like Petry, Edmundson, Chiarot, Gallagher etc. are not going to be impact players for the next Canadiens' core. There might be room to keep one around as a veteran leader but the choice is basically either to trade them now for future assets, or hold them and "lose" them to aging and attrition. RE: signing players, it really doesn't take very long to turn these things around. Toronto went completely scorched earth with 68 and 69 point seasons back to back. Their tank ended in April 2016, and 18 months later they were able to sign John Tavares in free agency with taxes, weather, and media every bit as unattractive as they are in Montreal.
I'm not someone that really supports a turbo tank and I don't want the team to deliberately go years and years without trying to improve, but I don't think there's really a way forward that doesn't' involve anyone older than Jake Evans being off this team in the next 3 years. I also think we're overrating Toffoli a little bit on this board, he's a good player but this is a pretty generic top 6 forward, not a can't miss 1st line stud.