For the last 5 years , or even more it has slowed considerably. Nvidia even claimed in a famous article that next generation manufacturing processes have no price benefit.
An interesting shift in the market can be observed in that demand is dropping at the high end compared to in the past. Partially greater economic effect, partially lack of demand.
The law might say the transistor density will increase, but if the market isn't willing to buy it, or the companies can't financially offer them, the law will fail but not for technical reasons. I think its a safe prediction the law will fail not for technical reasons but financial.
I don't think demand for silicon(measured by area) for high end manufacturing processes had dropped. It might have shifted from pc to tablets/smartphones. but it's there.
According to darpa , the end would probably come due to money. But even assuming unlimited money, 6nm is the size of a silicon atom. to go below we'll have to split the atom :)
