I used to regard Biggins as a jolly camp uncle sort of bloke, but watching him on CBB I can sense a nasty side. I really don't like him one bit, and unless he can keep up the act 24/7 for 4 weeks, he'll wreck the cuddly image and his "millions" of followers will desert him.
I can't see him pulling it off.

in the end it won't hurt him

they will simply have him back on BOTS again next series and rehabilitate him there the way they do--playing him as more of a wit and less as uncle fuddy duddy if need be.

It's only 48 hours into a 4 week run. Biggins won't cope with the kind of forced intimacy in the house. The jungle is different. People are getting territorial with the bed allotments (BB being really wicked here, mwahaha) and it will get more and more difficult for him to stay cool. He's already said in the DR he wants to get rid of one of the pretty boys, why I don't know but he's clearly got issues there. The way the young HMs talk about sex will wind him up, and when it gets beyond talking both Biggins and Saira are going to freak out. The bed situation alone will be a challenge, he won't want to share, and the few he'd settle for bunking down with won't want to sleep next to him. I wonder if he snores? Anyway, my money is on him blowing a gasket well before the series final and either walking or getting nommed on a weekly basis.

There is the first indication why he won't

I loathe him. </3

I look forward to his eviction.

Medically retired once he knows he won't win

He's already starting to crack. Channeling Jayne about the state of the "lavatory" and people not cleaning up after themselves. He's so obviously not gonna stay the course.

thats actually a good call on what might happen.

I could even see it being all pre-planned. a way to allow him to escape with his pride so CBB continues its grand tradition of protecting certain people.

I hadn't thought of that, but you're probably right. No doubt he has some kind of rider in his contract to protect his public image if he goes apeshit or walks.