Somebody or something comes out and removes the stuff that's been there a while. Which brings me to the next issue of the ability to manipulate objects together or as a group. Simple objects like a ball that could be kicked around. That's a great idea. In fact, this weekend I spent some time trying to create a library for robot builders.
Robots can be a whole variety of things.
For example, a kick ball would be a BOT that, as it sees people come up close to it, can get kicked and moved around. And it would understand both the people around it and the property around it. One of the things I'd like to do is put up a stadium where I could host a game. Like a soccer game or something. I'm not suggesting lots of objects that have shared capability or shared use or shared ownership.