Good luck of finding such place! I also noted that friends of my son were initially all from the same courtyard (obviously). Now the majority of them lives in a three kilometer radius. He has friends in a school, courtyard and in a sport club. They intersect only by a half. At this age you easily make new friends and also easily get rid of those with who you doesn't fit. I think, that the more people you meet being young on a different activities and can easily visit by a bike, the more chance that you will find the ones who will be your real friends through the life and the wider your world will be. This is another point to live in a crowded but cyclable area.