Don't ever assume the US is ever fully leaving - ever. THis is as long as Iraq allows it.
They want a permanent base for ops against Syria or Iran if the situation warrants it.
-S
PS. I don't doubt the US will step down if asked. This is the moment we have been waiting for. The Iraqis can now handle things themselves. This is exactly what we have tried to accomplish since 2003.

But of course, you said back then that we would never achieve this. :p