By Andrew Holleran There’s some growing speculation about a blockbuster broadcaster trade involving ESPN and FOX. With Troy Aikman set to leave FOX for ESPN, he could reportedly be joined at the Worldwide Leader by his longtime broadcasting partner, Joe Buck. However, ESPN and FOX might need to agree to a trade in order for that to happen. We haven’t seen a broadcaster trade in a long time, but it could happen here. Appearing on the SI Media Podcast with Jimmy Traina, longtime ESPN insider Jim Miller suggested that a blockbuster trade is possible. ESPN could make an offer to FOX for Buck, poss…