I think it is definitely something that is difficult to imagine until you are there and obviously, it is not for everyone. I only ever intended to feed for 6 months and even that was somehing that was difficult to get my head around. In the end though, it is no different to any other comforter though (blanket, soft toy, dummy) so if you are worried about developing a dependance than you would have to eliminate any form of comfort! I will tell you about my DD for example though. She is a few months from 3 and she woke during the night to be soothed by a breastfeed (right up till a few months back) but gradually, she transitioned to just needing to be near me, this then became less and less frequent. I believe the fact that she had grown up knowing, if she did need me I would be there as soon as possible helped her to be confident and independant, she was secure in doing so because she had the knowledge that if she couldn't quite manage it, I would be there and she soon realised, she could manage it because she had that safety net to try. It is hard to explain I guess but I feel children gain confidence and independance from realising the option is there, this isn't just breastfeeding but any comfort. I wouldn't want my daughter to gain forced confidence or independance out of neccessity personally.

My daughter is still breastfeeding and I am due with my second any day now, so not sure about the cut-off thing as my DD won't be cut off. They will be sharing! I don't know when DD will wean but I will happily feed her as long as she has the ability and desire, I imagine there is a strong possibility that they will wean at a similar time.

As for my partner, we both still enjoy stimulation in that area frequently. I'm not sure why breastfeeding would hinder that? The first few weeks there might be some difficulty while your supply settles down but past that point, there is no reason to not enjoy everything you once did. Not wanting to be too crude but a vagina or penis has two purposes, one of which is sexual whilst the other is not yet we still manage to have sex and reconcile this fact

ETA: It is a very different technique between a baby/toddler drinking and a partner partaking in adult activities, humans lose their suck reflex for breastfeeding as their mouth grows and changes so it is actually really hard for an adult to get milk even if they were trying.

I also think all of these things are concerns many people have when they are about to become a parent and the OP doesn't seem confrontational but curious. I think it is a good idea to explore these things and seek the knowledge/opinions from those who have been there whilst also being brave to put your thoughts out there.