As the buzz surrounding the iPhone 6 continues, it’s looking more and more like the next model will indeed be the iPhone 5S. Apple Inc. (NASDAQ:AAPL) is expected to release the next model sometime this fall, probably in September. If only the iPhone 5S is launched, will it be enough of an upgrade to convince current Apple fans to switch now, or will they wait for the iPhone 6?

Apple iPhone 6

Apple’s real iPhone 6 plans, will you please stand up?

The greatest question mark right deals with how many iPhone models will be released this fall. Many are speculating that we will see a low cost model along with the new flagship. We’ve seen photos of the alleged packaging for something called the iPhone 5C, and it’s unclear whether this device, if it exists, fits into the equation.

One thing that should be noted is that alleged leaks about the next iPhone have tended toward it being an S upgrade. The only rumors that make the next model stand apart from the iPhone 5 are the alleged fingerprint sensor and the 4.3-inch screen, and it’s debatable whether those features are enough to warrant the iPhone 6 moniker.

Demand for the iPhone 5S hangs in the balance

Analysts at Jefferies believe that when the iPhone 5S comes out, demand will be weak because Apple Inc. (NASDAQ:AAPL) users will skip it and wait for the iPhone 6. They note that replacement cycles for high end smartphones appear to be getting longer and that the greater chance for growth lies in the low to mid-range of the market. So even if Apple Inc. (NASDAQ:AAPL) doesn’t skip over the iPhone 5S as some speculate, users might do so.

Others though, like Apple guru Gene Munster, don’t think even the likes of the Moto X with all its fancy features will be enough to woo Apple fans from the iPhone.

Why the iPhone 5S might not be a total wash

Nonetheless, there is evidence that the iPhone 5S might do well in spite of Jefferies’ concerns. They note a possible floor on the number of iPhone 5S shipments we can expect in the next two quarters. Demand for the iPhone 4S was especially strong, and since we are now two years out from the launch of that device, tens of millions of users on a contract plan will be eligible for an upgrade.

In addition, the latest data from Kantar Worldpanel shows just how resilient the iPhone can be in terms of demand, not just in the U.S., but also in Europe and somewhat even in China. Raymond James analysts Tavis C. McCourt and Daniel Toomey estimate that iPhone sales in the U.S. grew about 52 percent year over year, mostly due to the addition of the device at T-Mobile.

Will all this iPhone 6 talk overshadow the 5S?

Apple Inc. (NASDAQ:AAPL)’s biggest problem in terms of demand for the iPhone 5S is going to be all the media speculation surrounding the iPhone 6. Have we so hyper-focused on the iPhone 6 that no one will want the iPhone 5S because of what the iPhone 6 MIGHT offer? No one really knows what the iPhone 6 will be like or even if Apple will keep the naming system intact. But the rumor mill has been churning out suggestions about what it might be like so fast and furious that it just might turn the iPhone 5S into less of a success than it could be otherwise.