"The Departed" Sequel and Prequel

I'm going to get this out before I force my fingers to type this. You don't make sequels to movies like this, you don't make sequels to movies like this, you don't make sequels to movies like this, you don't make sequels to movies like this, you don't make sequels to movies like this, you don't make sequels to movies like this, you don't make sequels to movies like this. While I'm at it, a prequel probably shouldn't be made either, but for some reason I can tolerate that more.
In any case it seems like the rumors are true. Mark Wahlberg, who is now an Academy Award nominee for "The Departed", talked to Empire Online recently and said he was asked to reprise his same role "The Departed" prequel and sequel. Here's what he said:

"They told me they wanted to try to do it and I said, 'Well, I enjoyed playing the character'," he continued, "They're talking about bringing in De Niro to play a senator or a congressman. You know, the corruption obviously going deeper and higher up the ranks — reaching up the political chain. So it'll be fun. And if it's a success, they're gonna do a prequel and bring everyone back... make it a trilogy."

Finally he said writer William Monahan is working on the script to a sequel and filming should start somewhere at the end of this year. Unless Scorsese has one hell of an ace up his sleeve (two actually) I find this to be a bad idea. On the other hand IF the next two films are anywhere as good as "The Departed" I will eat my words and declare Scorsese a pulp-storytelling genius. It has a lot of potential, I admit, but it just doesn't seem like this movie needs a sequel at all! They should ask me about these things before they do them, you know?