This article from Ad Age is bouncing around. The headline "Trouble in Store for Shopper Marketing?" is really misleading.
Firstly, "shopper marketing" does not just refer to "in store marketing" or POP. Secondly, even it it were, the fact that impulse purchasing is declining does not make it less important, it probably makes it more important. And certainly the fact that people are putting more thought into their purchase decision does.
But the biggest mistake is the notion that the economy is having dramatic impact on the fundamental nature of consumer decision-making. Unless it is overturning the result of evolution on the human brain over the last million or so years.