"IF the world is in a plateau--How long can it be sustained?"

I think one thing we forget is the size of the curve.  The base could be said to start in 1930 (or even go back to spindletop) and end in 2070 (perhaps dragging on in small volumes further).  Given a base of 140 - 200 years, a 10 year plateau/peak does not seem unreasonable - even for a perfect Hubbert curve.

This is quite true, I think.  We may have just started along the Plateau and could hang there defying gravity for a decade or so.  Things may only speed up once there is general awareness of what this Plateau really is.  

At this point, we may speed up towards the end of the Plateau due mainly to protectionism (nationalist hording of resources - i.e. what I think Russia is currently doing).  If this gets out of hand, then this period of "suspended stability" could end sooner than later.

additionally, while production/extraction may platea, demand will not.  exponential growth in emerging markets (as if china and india are merely emerging) will also shorten the plateau, or stated inversely, cause the inevitable decline to start sooner.
-PoP
Are we discounting or forgetting the destabilizing effects of the plateau itself?  And how those instabilities in complex systems such as financial markets and geo-political relations will affect oil production.  For instance, the extreme instability manifested in Iraq right now could easily lead to sabotage in the oil fields.  If Iraqi oil goes offline this coming year, oil will (at least) spike up to the $80-100 range.
I think Khebab is using just the geology to define the upper bounds of the supply, which establishes why this may actually be the peak plateau and not another interlude. The effects that emanate out from that are not as amenable to pure statistical analysis. As you note, they have the potential to be massively disruptive also but one cannot make specific predictions about how the overall system will oscillate out of control. Instead Khebab is trying to show that we're at the point where this oscillation can occur. At least that is my understanding here.