At this point in time Q4 2011 is the earliest it could possibly be, and that in itself makes me doubtful that Nintendo would release the system then ...
Personally, I think Nintendo will aim to be ready (internally) to release their next system in Q4 2011, plan for a Q2/Q3 2012 release and wait for details about Sony and Microsoft's next consoles before they announce the release date; and if there is no announcement from Sony/Microsoft by Q2 2012 Nintendo can announce their system is releasing Q4 2012. In doing this they can (effectively) match the release date of their competition, or they can release it after enough time has passed that consumers won't be upset without competition; and (if they're lucky) in the absence of competition, Nintendo could sell 30+ Million units before their competition launches (and secure focus from third party publishers).
