Seems like what they say about China echos what they used to say about Japan 20-25 years ago. And Japan kept on rising happily forever after.
Although you're right that much of the scared-of-China crowd are just people who've transplanted their fears away from Japan.
As for "China's economy has plenty of growth left in it": the issue is not the amount of growth, but the source and quality of the growth.
But the bubble will pop.