Yeah, I think it's possible. I mean in my case I've only loved one person in the past I've broken up with, and we don't live in the same city - let alone the same country, so maybe not seeing each other often helps as well. Most of the communication is via internet, phone etc. The sexual/romantic feelings for this person will probably always be there but so will the friendship. We started off as friends and well this is my take but I couldn't love someone and be with them in a relationship unless the friendship part was there as well.
If I had to choose between not having this person in my life and having him in it, I'd choose the having him in it. He's very precious for me and I just can't imagine not sharing living life with him. I do not want to underestimate the power of this kind of connection to someone, in my experience it is so few and far in between. And it would most likely just be about my ego if I cut them off.
Granted it's not always easy, it's hard for us both imagining each other committing etc. to other people. But in the end what is fundamentally important is the other person's happiness and if there's someone else that makes them happy in a relationship form, then that is simply how it is. In this sense I've never understood jealousy.
I think sometimes platonic friendship is undervalued and defined by certain norms.
I don't know how it would be with other people though, because our communication with this guy is very open and that makes things easier in a sense.
I can't be as close to him as I know I always will wish on some level, but that's life. We don't work well romantically, but speaking for myself, I love him on a level that goes far beyond romantic. I don't need to be in touch with him in regular basis either to be there in practical terms when he really needs me. I have stopped fighting back the feeling because it's just not going to go away, I can merely distract it. And I can and am in love with someone else as well now, dating somebody else, and they're just separate feelings, but both exist. I thought the old love would die off naturally but it doesn't seem to be so.
If I've ever truly loved someone I don't think it ever goes away. And it's worth it.