My daughter is almost 6 y/o and is finally transitioning into her own bed... not fully due to personal choice - which I feel is very important for a child to make on their own, but because by early August I will be having a new baby and 4 will not fit in our bed. Also, children WILL want their own privacy - everyone eventually does.
Truthfully, I've never felt the need to push her out before she felt ready, tho my husband has been harping on that the last year. He knew I was a co-sleeping, breastfeeding attachment Momma before we married, so I remind him he knew what he was getting. I also remind him this time is very short compared to the rest of the life of a parent, and as an adult he should be able to cope with not always getting to snuggle his wife.
Obviously - sex is not an issue - hellooo... I'm pregnant LOL - but many non co-sleeping Moms tend to think it would be an issue but it never is.
As for breastfeeding and co-sleeping... it's for many reasons.
1) COmfort level is so much better because you don't have to worry how baby is doing while sleeping. You can hear, see and comfort baby when needed.
2) You barely have to wake in order to feed your baby, breast is right there, baby is right there - latch on then back to the needed sleep.
3) I feel safer knowing my child is RIGHT there. Fires, break ins, storms, you never know what may happen and when the baby or child is on another room, it may be harder to reach them in time.