I think the title alone explains it pretty well. I'm not talking about specific scenarios like if men had women's or if women had men's sexuality or something in-between. No matter how, if this would be the case for a period of time long enough for the marked to stabilize itself, it would be very different from the dating market we have today. Many issues people are facing would be less problematic and some would even vanish entirely. The only remaining differences would be the ones caused by social stigma, and since those aren't as big, they wouldn't cause many problems. Feel free to ask questions if something isn't clear.