Perfect example for what you mentioned was Boston's 2015 draft.
They had 3 top 15 picks and completely beefed 2 of them. They still walked out of that draft with DeBrusk and Carlo, who are regulars in their lineup now. It's much worse than it should have been, but when you look back its hard to call that draft a disaster (Though imagine if they had taken Connor and Barzal in addition to Debrusk and Carlo? Yeesh)
Regardless, my philosophy has always been that if you get 2 regular NHL players out of a single draft, you're doing pretty well. JG has done a pretty damn good job backfilling the system with prospects/players from the drafts where they didn't have a pick until basically the 100's. Look at the 2016 draft, we may end up having a half dozen NHL regulars from that draft alone, even if they don't all end up playing here. Only one of those guys was picked by the Rangers.
I'm pretty confident in saying that they'll get at least 2 regulars out of the 2017, 2018 and 2019 drafts if not more. Maybe they won't all play here, but those who do will become pretty key contributors and the ones who don't will most likely be moved for pieces we need.