The Apple (NASDAQ:AAPL) iPhone 6 and iPhone 6 Plus phones are total hits, with news flowing seemingly every day claiming that "demand remains strong." That said, even though the iPhone 6/6 Plus ramps are likely to be robust for quite a while, there seem to be concerns out there that because the iPhone 6/6 Plus demand is so strong, Apple will have a tough bar to clear with the next generation iPhones (which I'll refer to as the iPhone 6s and 6s Plus).

While I must admit to wondering if Apple will actually see a year-over-year sales decline in the coming iPhone launch cycle, I do think that the company can bring a number of enhancements that could drive excitement and, ultimately, year-over-year growth. Here are some of the upgrades that I'm expecting and believe could drive yet another robust upgrade cycle.

Significant boost in performance, more memory

There's not much public about Apple's upcoming A9 processor, but it is widely expected that Apple will move to 14/16-nanometer FinFET manufacturing technology with the chip. If true, then performance-per-watt should go significantly up as a result of improved manufacturing technology as well as whatever architectural improvements Apple brings to the table to the design.

Additionally, we saw Apple move from 1 gigabyte of memory to 2 gigabytes of memory in the iPad Air 2. I suspect with the significant increase in compute and graphics power that Apple is likely to bring with the next generation phones, Apple will also include more memory. This would come particularly in handy, as many would likely note, if Apple decides to implement more aggressive multitasking capabilities in the next iteration of iOS.

Hugely updated camera

It is well known that Apple cares quite a lot about the camera subsystem of its iPhones and has generally made solid improvements each generation. Interestingly enough, according to John Gruber (via MacRumors), next year's iPhone camera "might be the biggest camera jump ever." He talks about a "weird two-lens system where the back camera uses two lenses and it somehow takes it up to DSLR quality imagery."

While "DSLR quality imagery" could prove to be a bit of a stretch, a significant update to the camera hardware and a significantly improved image signal processor inside of the A9 could make the camera experience on the next generation iPhone quite compelling.

An even more capable Touch ID

Next year, I believe that Samsung (NASDAQOTH: SSNLF) and others will start to move to more capable area fingerprint sensors similar to what Apple has on its current crop of iOS products. In order to stay at least a step ahead, it might be time for Apple to introduce a significantly enhanced Touch ID mechanism.

MacRumors reports that Apple recently filed some patents showing an enhanced Touch ID that can track the motion of a user's fingers. Now, as MacRumors' Mitchel Broussard points out, "while inventions disclosed in Appel patent applications frequently do not ever appear in products, they can still offer some insight into Apple's areas of interest."

Apple is clearly very interested in Touch ID, and I would not be the least bit surprised if next year's iPhone features a vastly improved version of today's Touch ID implementation.