First, we should trade these players only if we get equal or better value in return.
Elvis is awesome and I love him. He is also an undersized, situational pass-rusher whose stock will never be higher and who is going to command MONSTER money whether he stays in Denver or goes somewhere else. I still feel that much of Doom's success is attributable to Mike Nolan and that we should capitalize on his success by trading him when his value is at it's highest.
Similarly, I love Marshall, but his stock will be soaring after his 21 catch game and strong finish to the season. He's a great player, but if we could get two 1sts and a 3rd or something like that for him, I'd trade him in a heartbeat. He will also command RIDICULOUS money and I think we could get great value for him, as opposed to before the season. I also think he is still more of a me-first guy that doesn't fit into McD's plan and, remember, he's always one character slip from a one-year suspension.
We have a strong team, but it's an older team. We need to continue to infuse youth and speed into our secondary and youth, size and strength into our front seven if we are going to sustain success. And, as shiny as the elite WR and marquee passrusher are - and I love both of these players - to sustain success in this league, you need an abundance of talent on both lines and throughout your team. We need to fortify the interior of our O-line. Our D-line needs to be upgraded at every position. We need inside linebackers galore b/c Andre Davis has maybe 1 or 2 years left. We need another talented corner and likely another safety. We need another OLB and probably another running-back (as crazy as that sounds).