Flo said, yes, we won't need marriage in Heaven, because we'll all be family.
My unspoken response was ... well, it was incoherent, but it centered on the fact that for many people, SEX is an important part of marriage.
I already had plans to exegete that passage in a pro-poly way, so there's a way in which that works for me -- about sex not being something that needs to be limited to one particular relationship, but is an experience that can be shared with many (I'm reminded of Desmond's frequent analogy to food) -- though it also has implications of that troubling idea that often shows up in queer theology that all our differences will be erased in the eschaton (relationships are particular, and ceremonies like marriage honor that particularity; relationships are neither identical nor interchangeable, and that is not only okay that is GOOD).