This will be a test to the character of Keith Thurman. A true champion in this sport of sweet science can bounce back after a loss so i think Thurman will handle this hurdle with pride and a mindset of a true champion.
For me, he is one of the legitimate contender for this loaded welterweight division and he could defeat Spence and Crawford if given the chance to fight those champions in the future.
Yes, and this maybe the reason why Keith wanted to come back, the timing is perfect, Spence and Crawford, who is the best right now could be available to him if he will win his fight against Barrios.
And he himself said that those two are the top right now and it will be a big challenge for him to fight them. But he has a big hurdle first to overcome and if wins over Barrios then wait for the winner of Spence vs Ugas or go directly to Crawford.
As for the ring rust, it's two fold, sometimes the fighter that takes a lot of break can come back strong and rejuvenated.
Thurman still has the skills, and if continue to make himself fit through proper training and diet, then he should not experience the ring rust in this fight, besides he is still the favorite, so that's a big thing that people still believe that he can win in this fight.
And yes, this fight is a big one, it's his ticket to a fight against Crawford or Spence.