Right now, teams can only trade three year's worth of draft picks. After the draft is completed, the next set of draft picks is available for trade. This number used to be 5 years, but with ownership turnover the way it is, that needed to be reduced.
I would like to have a bit more wiggle room for trading during the draft. Picks are flying during the draft, and would like that next year to be opened up at the start of the season instead of after the draft.
This would be something low priority, but I think it would be a good change.