Could I date a transsexual? Why yes, I could. I could also just date another guy. I could date someone thirty years older than me. I could date a pornstar. Hell, I could date a walrus. There are all sorts of things I could do, hypothetically, because the possibilities are endless, especially when it comes to attraction.
Though in fairness, the matter of walruses is slightly more cut and dry.
Truth is, though, it's not something I see myself doing. Which is no sleight towards all the transeseses out there. I don't see myself dating a fundamentalist christian or a Saudi Arabian, either. Hell, right now I don't even see myself getting a new haircut.
However, I won't rule out the possibility that there is a transwoman out there who has the potential to be "the one". Just haven't met her, is all.