While most analysts believe there is nowhere for Apple’s stock to go but up, there is always at least one naysayer.

According to AllThingsD, BTIG Research’s Walter Piecyk cut his rating on Apple’s shares from buy to neutral. The main reason? Those wacky and wild wireless subsidies.

“Subsidies by post-paid wireless operators have fueled the growth of Apple’s $600 iPhone since its inception,” says Piecyk. “Wireless operators have been happy to subsidize smartphones to new and existing customers in order to provide a lift to the average monthly bill (ARPU) of their customer base, a metric which had been falling for the past three decades.”

So, boiled down, wireless companies (starting with AT&T) are rolling out stricter upgrade policies, making it harder for users to get the newest iPhone every year at an inexpensive rate.

“We expect post-paid wireless operators to remain firm in their plan to stunt the pace of phone upgrades in 2012 and we expect to see some initial evidence of their success in the current quarter,” Piecyk said.

With that, the analyst said he believes iPhone sales will drop to 27.5 million in the third quarter for revenue that is $1 billion less than consensus.

I don’t know how much I can believe this line of thinking. Even if wireless carriers follow AT&T and make it harder to get the lowest price for the new iPhone, how much would that stop customers from waiting another year?

If the sixth generation iPhone is as big of an upgrade as we think, would you hold off on buying it without the largest carrier subsidy?

(Image via DigitalTrends)