Worst case scenario, Thurman gets KOd.
He's fought no one as good as Shawn Porter yet and has an extreme tendency of getting on his bike once the fight is brought directly to him
He's also not shown the ability to deal with inside fighting either and we've seen him visibly hurt inside the ring due to body shots....and that's Porter’s Forte (inside work/body work).
Porter is not going to box with him, he's coming to maul & brawl....Bundhu/Guerrero fight showed that Thurman doesn't deal well that type of pressure.
I don't see Porter KO'ing any top level fighters, more of a accumulation guy and I don't think he will hurt thurman at all, unless he just gets lucky.
I'd say Guerrero and Chaves are on the level of Porter and that is how poorly I see Porter as a fighter.
I wish I could say Porter was a good inside fighter, but I don't see it, he throws some nice body shots, but on the inside, nah, he is a little too wide and too square on the inside for my taste.
Porter coming to maul and Brawl will see him eat jabs and straights all night while opening himself up to Thurman's power and being hurt badly.
My opinion but I don't rate Porter highly at all and think he gets outclassed badly by a guy who is a level above and have more power and technique than he can handle.