I think you love playing GM a little too much. Trading for future 1sts based on projected finishes that season feels like a fools errand.
If this is the 16 team league you have Fields & Lawrence AND your rebuild is almost complete, I would still take the QB.
In another thread I was suggesting you take Richardson for the upside, but in your situation I can see the argument for Young. QBs can have a ton of value in SF leagues, if Young, who is the day 1 starter in Carolina and as game ready as they come, can match Mac Jones production as a rookie you should be able to find a QB needy team next off-season and unload him for a premium.
Don't bank on him becoming the next Brees, it is so very unlikely, but sell him to an owner as if he were the next Brees.
You should be able to land whatever missing piece, or picks, you think your team needs.