The launch date of Apple's (NASDAQ:AAPL) next generation iPhone -- known for now as the iPhone 6 -- appears to be fast approaching. While the exact launch date is unknown to all but to a chosen few, it's probably safe to bank on a mid-September launch. Though the wait seems torturous, we can bide the time by taking a look at everything that we do know about the phone so far, and ultimately what it will mean for investors.

It's bigger
For quite a while there was plenty of speculation around what size(s) the new iPhone would come in. After reports that Apple was testing numerous sizes, the consensus now seems to be that the standard model will come in a 4.7-inch size and that a larger variant will come in at 5.5 inches. No matter what Apple's launch schedule looks like, it's clear that the next iPhone will be larger than the current one.

Although the iPhone 5s due with just a 4-inch screen, it is still the world's best-selling smartphone nearly 10 months after its launch, outpacing Samsung's Galaxy S5 (aka "The Next Big Thing"). Though consumer trends are very difficult to predict, it seems almost like a no-brainer at this point to expect Apple to gain significant share with its newer, larger iPhone models.

It's faster
The next generation iPhone will likely feature a next generation, Apple-designed "A-series" chip. The chip is very likely to be built at Taiwan Semiconductor (NYSE:TSM) on its 20-nanometer manufacturing technology. This should allow for significant performance/density improvements over the current generation A7 chip (and should provide a boost to Taiwan Semiconductor, even if it is temporary). 

The new chip is likely to sport a fresh pair of Apple-designed 64-bit ARM-compatible processor cores, bringing to the table a sizable increase in performance. In addition, though it's not entirely clear yet, the A8 could either sport Imagination Technologies' next generation Series 6XT graphics architecture or a home-grown Apple-designed graphics processor. Either way, graphics performance -- by virtue of the added chip real estate that the 20-nanometer process brings -- should be way up in the iPhone 6 (meaning that games look more realistic and run more smoothly).

It's covered in sapphire?
Ever since Apple signed a strategic supply agreement with GT Advanced Technologies (NASDAQ: GTAT) to get its hands on massive quantities of sapphire, it has been speculated that the next generation iPhone will ditch Corning's Gorilla Glass for a sapphire cover glass.

YouTube tech star Marques Brownlee got his hands on what seems to be the front cover for the iPhone 6 -- and it looks as though it really is made of sapphire. Motley Fool senior technology specialist Evan Niu calls this move to a sapphire crystal display cover "brilliant and perfectly timed," and given how nearly unbreakable the display seems to be, it's hard to disagree.

What about margins?
The new iPhone will be jam packed with new features and enhancements relative to the prior generation iPhone, so of course there will be concerns about margins -- at least initially. There's little doubt that the components will be a bit more expensive on balance, and the new industrial design probably won't yield as well as the current, two-year-old iPhone 5/5s design, so -- barring a price increase -- Apple is likely to see a bit of gross margin pressure.

That said, if Apple can drive significantly higher volumes (which is the expectation), then this is more than likely to offset any per-unit gross margin loss.

Foolish bottom line
The next generation iPhone is likely to be the biggest launch that Apple has ever done -- both literally and figuratively. The phone is likely to be compelling enough to keep the vast majority of existing iPhone users that are looking for an upgrade, and at the same time could bring back customers that prefer iOS but had flocked to Android in search of larger screen sizes. If this thesis plays out as expected, then not only will Apple grow its share in the premium smartphone space, but it will solidify its dominance as the world's most profitable smartphone vendor.