> The mind share for that word went down. Instead we found ourselves hearing people asking for Prosecco or bubbly. Champagne might now be able to assert that only the'quality' product from their region has the name, but I suspect it's just caused the companies that produce wine to make sure that they own the trademark, and push their brand, not the term champagne. Regardless of whether it's from that region.
I haven't noticed a substantial change. Most people in the US I meet that aren't really into wine still use "champagne" to refer to sparkling wine. I was actually looking at making mimosas the other day and picked out a bottle of okay sparkling wine (it seems silly to mix expensive wine with OJ to me), and my SO commented that mimosas she thought mimosas had to use champagne. I picked her brain about it (I was shocked someone would pay for champagne for a normal Saturday mimosa), and she thought champagne was a totally distinct thing from sparkling wine. She thought sparkling wine was force carbonated like beer, or maybe just flat wine mixed with seltzer water like a wine spritzer. She didn't know what prosecco was, and when I told her, she said she would call that champagne.
I don't think their campaign has had much of an effect on the average American. It makes a difference to connoisseurs, but the average American doesn't know the technical difference (and likely has never had true champagne, because of the relatively high price).
I find that's generally true of culinary things in America, though. Many of my friends buy their wine from gas stations and are happy with it, which I struggle with. They typically only stock bottom of the barrel stuff like Barefoot; the white wines taste more like apple juice with vodka mixed in it than a real wine. The reds are generally exceptionally sweet; even full bodied reds lack the flavor and feel of tannins (probably to increase the appeal among people that hear cabernet sauvignon is a good wine, but don't know they don't like full bodied wines).
It's really a shame. There are some quite good wines in the cheap range (especially if you go for less traditional regions, like South Africa), but gas stations don't carry them and people tend to judge the region for unfair reasons. I get shocked looks if I open a bottle from Argentina or South Africa, as if wine is only meant for the wealthy and the grape vines can sense if they're in an economically disadvantaged country and will refuse to produce good grapes until you transplant them to a country with a higher GDP per capita.