Going on the points chart our 1st is worth a 1000pts, the trade with 49ers would be worth 820 without out picks/future ones added. It would take a huge haul to tempt me to trade back that far and for the draft board to completely collapse at that point. (Passrushers, Safeties gone and no one taking any of Quarterbacks)
I wouldn't be against trading back but I wouldn't trade out of the 1st round for just a 2nd and 3rd.
If your looking for a draft haul something along the lines of trading with our 1st to Cleveland for both their 2nds and combination or 3rd/4ths would be more appealing (2nd 2nd 3rd comp and 4th). This would give us three 2nds, three 3rds and two 4ths .... 7 in the top 100.
Could only see browns trading up that far it they didnt take a QB with their first 2 picks and one had fallen to that point they really liked Trubisky/Watson and thought one of the next few teams will.