I think I would have to say yes...
We'd start Cousins at Center, allowing KG to move to PF.
We then have Bass to back up KG and Collins/Milicic to back up Cousins...plus Cousins is young enough that he can play big minutes, meaning Collins/Milicic would really only need to play 10-12 minutes a night. Then we still have Wilcox as well.
At guard we still have Rondo, Lee and Terry...plus we could still add one of the young guys we've picked up from summer league.
The loss of Melo ironically would probably be the one thing we cant really make up for, but with the potential of Cousins you wouldn't really be as concerned - he has the potential to become a top 5 big man in the next couple of years.
Giving up three young guys does make giving up a pick hurt more...it means we can't pick up another young guy throught he draft.
It would be a very, very hard decision for me because you're throwing away three guys (who all have the potenial to be starting calibre guys three years from now) for a single guy with the potential to be a future all star.
In the end I'd probably do it because as I said in another post earlier, solid players win games, but superstars win championships.
Personally, I'd still be happier probably getting Josh Smith, as I don't think we'd need to give up AS much for him as we'd have to for someone with the youth and upside of Cousins.