The hole is not at large as you think it is. But I'm not surprised that everyone has their panties in a wad. It's all you see and hear in the media.
Going by 2024 numbers, Buffalo scored 269 goals which puts them 9th in league scoring. JJ scored 27 of those goals.
If Buffalo gets 13 goals from all the new players added, that includes Norris, in 2025, they with have 257 goals, which would rank at #12 last year. That isn't a big drop.
But now what is all the defensive improvements lower your goals against by 20 goals? Your +/- actually improves.