I'm not sure that BOB would be willing to bring in Mallet (via a mythical trade for Johnson) at this point, mini camp is over, he already has something like 23 QBs in camp (granted they all stink), but it seems like a reach at this point.
That being said, Johnson to NE would be amazing! Let's see what happened the last time Brady got a true #1 WR, oh yeah, they went 19-1 (f&*k Tyree), and Brady threw 50 TD passes in the regular season.
Johnson has a lot of money coming to him (@23 million over the next two years), so anyone who trades for him is going to want to restructure. Houston will take a huge salary cap hit, so any trade really has to be worth it for them.
Houston gets: Mallet, Cannon, and a conditional 3rd round pick, which will escalate to a 2nd round pick if the Pats make the AFC Championship game.
Pats get: Andre Johnson
This way, Houston gets Mallet who can compete to be a starter. Cannon, a young very good lineman, still under his rookie contract. Plus a third (almost sure to be a second) round pick. I think its a deal both sides can live with and sell to their respective fan bases.