Negative interest rates aren't technically bad. The interest rates are 0.4% underneath inflation rates. USA interest rates are 0.2% beneath inflation. Germany is 0.4%, Canada 1.1%.
The China part, you are alright about that. The Chinese economic progress is slowing down, but I don't honestly think that'll lead to a global financial meltdown.
This is the true problem here. The USA debt crisis, which seems to be growing despite all the government control that attempts to quench the flames.
In a sense, the USA acts like the kind-of Ottoman Empire back in the 19th century. All the other superpowers have their eyes glued on the USA and the dollar, trying to figure out whether it'll be able to heal itself or if not, when it will go down.
I honestly hope the USA will find a permanent solution to this issue, a major financial meltdown could possibly de-stabilize the whole world and ruin all the magnificent progress we've made in economics over the past two-and-a-half decades (even when you count with 2008-2009, world poverty rates were halved).