I commented below on this, pasting here, because I agree--oh do I agree--but a secondary fallout from doing it this way:

You know, you hit something with that, especially if they do go the romance angle; it's a very specific kind of commentary on television--and hell, society--that apparently it is only joint penises that inhibit true love. Literally, with this translation, the only reason Watson and Holmes aren't doing it is because they're the same sex. And yeah, basically would confirm years of subtext of yeah, that potential has always been there after all if all you need to do to make it work is flip one character's sex/gender.

I mean, it kind of kills the entire "BUT IT IS NOT THERE AT ALL EVEN IN POTENTIAL" when, literally, the only variable difference is a female Watson. If it's perfectly workable as a romantic pairing once Watson is a woman, then Holmes/Watson dynamic in male/male form does have that potential.