So, the initial protoplanetary disk was more massive on the outer side of Uranus/Neptun since they migrated outwords even the disk was less dense then inner disc from wich all inner planets were formed and despite majority of debris disk's mass (Jupiter/Saturn et al.) was located in the place between the Sun and U/N system? (Do I smell Dark Matter here? :-))
The planets swept out traces of the debris disk, how come they forgot the Asteroid Belt?
What is the relevancy of something "that could happened" in the context of science? (I thought it was art that is dealing with that.)
I mean, is Nature some sort of "popular science"?
Recently, in arxiv, a paper popped up, where it was shawn that Jupiter could travel through the solar system end cause Asteroid Belt formation, tilt of Uranus end Gud knows what else..
Really, isn't it just a matter of choice of initial conditions (i.e. stable and unstable resonance)?