First off, I purposely only read the first post here -- so if i repeat something, sorry!
Anyway...I like the Wraith, but I don't think they are going away. I think they are going to be less of a concern...i think they new hybrids will be worse of a threat (like others have said...he is smarter, and I think it was because he was with us for a short while). Also, he has "help"....
But, with that said, their bio-tech wont go away because of Micheal -- he knows wraith tech, why would he make different ones? But really, Season Four/Five will probably be like season 7/8, where the goa'uld became less of an enemy, and the replicators become more of a problem...but in this case, its' the Wraith are less of a problem, and Micheal and his hybrids become more of a problem.
But I do think that Todd will survive. And I think he will be our greatest enemy in the end -- I mean, he worked with us, knows how we think -- hell, he alone might know where Earth is (he was at earth, and who knows...maybe he put acvtivated his tracking device...and the spoiler tag could have posible spoilers for season five or the rest of the season)
.
So...yea.