There's obviously huge respect between Pop and Sheed. They embrace each other whenever the Spurs and Pistons meet, and Pop has gone out of his way numerous times to praise Sheed, at one point during the 2005 season calling Sheed "a top 5 talent in the NBA".
The are some interesting scenarios going around, but i dont see anything happening via trade. The most likely possibility is Pop waits until the off season and they offer him something starting at the MLE, for about 3 years. Theres no secret Sheed has one of the best basketball minds of all the players, so i dont think he would have a problem picking up plays and fitting halfway through the season, like he did in Detroit, but I cant see the Pistons taking anything from the Spurs in a trade, outside of the big 3.