Ninty won't be in trouble for the next 10 to 20 years, even if they sell 0 hardware and 0 software in a near future...
With all the money they've been makin' on both software and hardware, they're richer than ever, and no sales decrease could REALLY affect them...
Just look at the DS and Wii userbase: how long before PSP and PS3/360 could reach 100 or 50 millions? Never, or maybe by the end of this gen... at best...
No, the only way they could be in trouble is by loosing money on each Wii ever sold, or by the need of massive sales for games with a 50 to 100 millions dollars budget...
Wisely, they just left all this for the competition: so, who's REALLY in trouble then?

"A beautiful drawing in 480i will stay beautiful forever...
and an ugly drawing in 1080p will stay ugly forever..."