I don't believe so. I'm not one to really think about 'possibility' in that sense at all, though; essentially, if someone has the ability to change, they will, because that's how the sequence of events determined it. It's why I'm not satisfied with answers like 'yes, if they put in the effort or have the desire to'. Because that just narrows it down; now we're not talking about all bigoted people, but those with certain traits.
And what triggers this desire to change in the first place? We know the same event or piece of information won't change every bigot, otherwise we'd have a tried and true way of brainwashing by now. Despite identical personalities or behaviours on the surface, there's still so much we don't know about the inner workings of someone's mind which makes it impossible to make broad claims like this. I'd liken it to genes; someone might have the same trait, but one person might have two dominant alleles whereas one might have a dominant and a recessive, and we simply can't tell from the surface. Likewise, perhaps a bigot has potential to change if you expose him to a certain event, but another wouldn't, even though their beliefs and way of thinking are seemingly identical.
It's why instead of thinking that "they have the potential to change but just choose not to (I don't believe 'choices' can be seen so simply)' I think it's more accurate to say that the method of changing someone isn't universal, if we can even say that it exists for someone at all. This kind of thinking is behind why I think that ultimately, the idea that "only you can change yourself" is a lie. Of course, I'm not saying that it's other people's responsibility to change other people, but I think the idea that only you can change yourself exists because people believe that if there's an opportunity to change someone and you don't take it, it's your fault. I don't believe that. I think you absolutely can change someone in certain circumstances if you put enough time, effort, and love into changing them, and that in fact it's sometimes required. How many cases have you heard of someone receiving support, new relationships, or even advice that helped get their life back on track? A lot of people's motivation could be solved if they had someone who cared about them that pushed them into beneficial situations or took care of them in some capacity. It just doesn't mean you have to do it, especially if you're tired and have issues yourself. It's tiring to support someone, never mind take care of them. And it's certainly not a guaranteed method of 'fixing' someone either, just like leaving it to themselves isn't either.