Quoting: CheechYou
Yes, this makes sense at first glance. But one point that I think often gets overlooked is that 1 or 2 of these investments on very good 29/30 year olds players should be looked as partial investments into the development of your younger players themselves.
Celebrini, Smith, and Musty's development will absolutely be progressed with a guy like Marner/Guentzel/Reinhart on the team in their early years. There's a good chance that their development is stagnated either in small part or in great deal if you don't have those guys on the roster to help them and the team out.
A few counterpoints:
By adding those guys, you'll reduce the value of your draft picks for the near future, thus lowering the team's potential.
Who needs 30 year old superstar linemates to help their development? That's a silly suggestion. None of Orr, Gretzky, Lemieux, McDavid had that. Even lesser players like MacKinnon, Matthew's, Kucherov and Marner didn't have (or need) that.
The best teams in history have a core group of similar aged players.
By the time Celebrini is in his prime (25-30), all those older players will be well past theirs or will have aged out of the league.
You can always sign a bunch of UFA's in 2 years.
Don't rush the rebuild, do it right. Accumulate a bunch more talent before pushing all your chips in.