First we'd have to see if GS would be willing to make such a deal. The one thing i'd caution against is this idea that just cuz we have strong feelings for these draft prospects that somehow we know for sure that they will pan out to be as good as we hope. The entire reason for going with FA's and paying good money is that you do in fact know what they can do and at the least have some frame of reference for what you think they will produce.
I'm not sure that Phil is willing to take that many chances on young prospects. We have to start being realistic. The Knicks are not going to turn into the Sixers or T'Wolves. They clearly want to have a much better season next year using the FA Market and then likely doing it again the next summer. There are relatively young FA's who can be acquired and would form a good core for a good run of years. I think that's what Phil is thinking.
Phil is thinking that he can draft a young player for the future and put a new core of vets together who can win now and still have a great future once he gets past 2016 he has all of his 1st rd. picks. The next 4 years he can win games with vets and develop young players behind them. It's less risky for him than going with even more kids and waiting for them to develop enough to go deep in the playoffs. Phil is thinking Bynum and the Lakers vets were able to win as he developed. Bynum had health and personality issues, but if he didn't that plan would've worked long term.