I agree - that is quite a difference. The Hawks would be much more potent offensively. If Delia rounds out and is an average goalie then with the reasonable notion that Strome, D-Cat, Joker, maybe Kahun and a few other young guys being incrementally better next year relative to this year --- making the playoffs in the West is quite doable. I would expect it actually.
But i would also expect that such a roster - in the absence of bringing in 1st pairing people (and, at what cost?) --- would make for a very early exit from the playoffs. Ultimately, far more often than not, the teams that make deep playoff runs do so more on the basis of lack of (or modest) weaknesses to exploit and not so much on strength of strengths. That is, one of Panarin or Stone and one of Kakko or Hughes would strengthen the Hawks strengths (as it were, while our forwards and not great by any means - they are the relative strength of the team). But it would not address the weakness that any playoff team that faces us will exploit.
My position has been - and remains - that something meaningful (like deep playoff runs) will be possible only once the blue line deficiencies are resolved, and no sooner. Panarin or Stone and one of Kakko or Hughes --- their addition would help - but is that the best expenditure of resources? Tough to say.
But you are correct, I'd think, the addition of two of these you mentioned makes us playoff caliber. it is just that a roster loaded up at forward but with unaddressed D problems is going nowhere --- even if they get 4 extra games.