I like the idea !
The user become a part of the page...

I sometimes think that wireframing applications should have an animation software oriented method. Instance are like frames in a cartoon (a very short one).
flash or after effects have a way to group sequences and subsequences ("clips" in flash). Then, when the instance fade out, it can be retrieved in its clip at its position, a subordinate state.
Somewhat like a time line is an other idea to model any type of interaction...