The average new Porsche buyer in 1985 would care.
The average new Porsche buyer in 1995 didn't care.
(Boom economy but no interest in Porsche)
The average new Porsche buyer in 2015 doesn't care... at all.
The new Porsches will all be quicker than anything that came before it.
They will suck down less gas. And there will
still be a metric ton of used water-cooled Porsches that go faster than the dwindling supply of air-cooled cars with still relatively low costs to maintain. So for 'cars and coffee', track, AX, or just parked in the garage until the next impulse purchase takes its place, water-cooled either NA or VW Turbo, will suit 9 in 10 used Porsche buyers just fine. The one guy objecting being the one who wants to row his own gears (a shrinking pool), is nostalgic about Porsche and actually has enough money to keep bidding these air-cooled prices yet higher (another shrinking pool in the long term). The millenialls as a class, only care that it's a Porsche, they don't see the fuss in water-cooled vs. air cooled, or NA vs. Turbo.
Conclusion: this changes very little other than making Porsche even more profitable as it will no doubt be cheaper for them to make more power with these VW turbo engines. I don't buy this idea that it's because they have to meet the gubimint standards. The bulk of the sales for Porsche are from the SUVs and sedans, and will eat up even more of the pie going forward. If the standards going forward remain on a fleet basis (targeting the models that actually rack up mileage like Cayenne), then these non-purist Porsches could do nearly all the heavy lifting to keep MPG's above the very low standards set by the U.S., while keeping the smaller % of sales from the beloved flagship variants on NA power. The Maccan
is predicted to push Porsche north of 200K cars this year. And if Porsche were to fall below the fleet standards, the penalties would equal a tiny drop in the ever-growing Porsche profit, largely thanks to globalization, Chinese billionaires, etc.. Bottom line, Porsche could
easily afford to keep the 911 NA nostalgia going in avoiding these VW Turbos. And it could arguably be more profitable to simply pay the fines and meet the purist demand for their very high margin NA 911's. This is Porsche we're talking about here, not Lotus or Caterham.
If Porsche are getting behind VW Turbos, it's because they like the other kind of green, the Ben Franklin kind.