The impact of a QB is a few times greater than even a rush end/LB. There will be a QB at 3 that should be successful in the NFL. If Pace has identified him, he should take him unless he feels he's assured of getting him later but that type of assuredness is what got our last 2 GMs in trouble. JA trading down, expecting certain players there to find them or at least his preferred options gone, made for some very odd drafts with selections like Bauzine and the pool jumper. Obviously, If pace doesn't feel good about the prospect, go elsewhere but I suspect that if only one QB is gone, it will be hard to pass on #2.
Even if next years class is that much better. I suspect we pick outside the top 10 and it really doesn't matter if there's better than whats here this year, they'll all be gone by 10. This is a (hopefully) rare opportunity for the Bear. No none is saying take one just to take one but the long game would have you do so if you like the prospect.
Look what's happened to playoff teams without their impact QBs. Much, much worse than if they missed their impact LTs or pass rushers. What you can get by with in the regular season is different than post season. Playoff Ds need to be wary of both phases of O and can usually take one thing away.