There isn't going to be one according to
this (long) article. "In 2008, the only prevailing trend is that there are no prevailing trends."
It takes the view that there won't be anything 'big' because the idea of a trend hierarchy has gone, and a million fragmented self-referential scenes can co-exist without following any trend 'authority.' (I would argue that this situation actually makes it ripe for the re-establishment of a unifying voice that collects this stuff together and guides people /filters stuff, but we shall see.)
More important is, I believe, the lack of a linear time line on trends. The word trend is bound up with the concept of time. Fashions used to go out of fashion because they came along, got tired out and we moved on. Old music was rubbish because it looked dated and its what your parents listened to.
But in a totally on demand world - What does 'next' or even 'new' mean?
I would argue that, to a teenager, new doesn't only mean 'just invented', it means 'just undiscovered' too. The Pixies have been around for years, but you could find them, removed from any sociocultural context online and enjoy it as if it was just released.
There is no such thing as 'old music' on the internet - it's all there as gleaming and fresh as the day it was produced. Even old news and old video content crops up in searches as 'important' as the day it was put there.
The internet has tamed the past and I can't wait for the future in my on demand world -
everything is 'so now'.