What year?

2012 - 2013 will be most likely.

2012 at the earliest IMO.

I think 2012 is the year for Nintendo. Although if they keep selling software at the current rate, they may never release another console.

Likely Q4 2012 worldwide. I still think there's a slim chance Japan may see it earlier though (as soon as Q4 2011).

I'm thinking 2012.

it should be kept on the back burner until the wii slips in sales. no point undercutting their successful console early. The wii is still the top selling console this generation but there is no guarantee nintendo would be the top seller in the next. best not to risk it until it is absolutely needed.

Q4 2012 worldwide

I went for 2013 or so because it was as good a guess as any.

I expect the next Nintendo console to come out very close to the next Sony console (whenever that is).

At this point Nintendo is most likely is a perpetual state of readiness - they will always have a protype ready that could be their next console - and as soon as Sony shows their hand Nintendo will demo their current prototype and give us a date.