People fall in love with people, not genitals. I consider myself as straight as the average slide rule, but who knows? The right woman may come along and I may fall in love with her, in some theoretical future where I was single.
If you watch I Kissed A Boy, you'll see that Lars (who is trans) has absolutely no issue pulling one of the fittest men there. In the follow-up show, they are shown to be deeply in lust with each other.
I have a trans son. He's been out for many years now, and I consider him to be...him. I don't look at him and feel conflicted- I just perceive him as a trans man, because he is.
Trans men are perfectly normal people, and falling in love with someone depends upon charisma, shared interests and personal attraction.
I think I could fall for a trans guy, yeah, personally, because the older I get the more I realise it's about how much confidence and (often) how they rock a cool coat that matters.
Anyone can fall for anyone. I guess if you hate trans people and have no respect for their existence (hi Mumsnet!) that would be an issue for you though.
I mean, I cannot be alone on here in being the partner of someone who's got prostate cancer. If the surgery leaves him impotent, for however long, we'll be having other forms of sex. It's completely reductive and quite horrible to reduce men to whether or not they can penetrate you with a penis. There is far more to sex, and attraction, than that.