Nothing will change. If anything, Bryan being in the chamber match (which I expected would happen anyway) is just a way to set up Bryan/Sheamus for Wrestlemania. I picture something like Bryan eliminating Sheamus and "The Celtic Warrior" becoming a sore loser as a result, leading to him Brogue Kicking Bryan as he (Sheamus) makes his way out of the chamber, which causes Bryan to lose the match. Sheamus may even become endorsed by The Authority and become on-screen buddies with Triple H as a result (maybe something about how "Sheamus - not Daniel Bryan - is the next face of the company after Orton's time is done, blah blah blah"), meaning Bryan defeating him at Mania is a way of getting a small victory over The Authority.
As for Lesnar, he'll probably be put into the chamber by Maddox next week or something. It all depends on what they decide to do at Mania - Batista v Orton or Batista v Lesnar. No way is Lesnar/Orton happening at Mania.