Wall street type people have long called apple a one trick pony (on so many words). They've been want see apple with a more balanced product offering. While Apple has many products and services, none of them come close to generating the amount of revenue the iPhone does.
I think the point is, that apple has a single product where it derives most of its revenue from.
And it's something I've said before and will repeat. This is why Wallstreet (for good/ bad it does) has issues with with relying as much as Apple does on the iPhone.
I keep reading people say "without the iPhone, Apple would still be super profitable multi-billion company on the remainder of their other products".
I argue (obviously hyperbolicly, since this is speculative and hypothetical), that without the iPhone, Apple would likely be still a small player.
The reason for this is because if you look at their product offerings. Almost their entire product catalogue has been assisted, or influenced by the iPhone. The iPhone is Apple's Halo product.
If the iPhone wasn't the success it was, not only would iPhone revenues not be where they were (or existing), The services portion would be next to nothing, if it exists. iPads would likely not exist, or sell well. Brand name recognition of the iPhone has absolutely helped sell Apple PCs. Most of the "other" category is accessories and items for i-devices (eg Watch).
Without the iPhone's rampant success, Apple would likely be a tiny PC vendor, if they still existed. iPods would have likely died out by now as well since most people were already looking to move MP3 / Media playback to their smartphones (Believe it or not, Smartphones did exist prior to the iPhone, and could play MP3's. Convergence was already happening long before the iPhone was released)
Its this that has investors worried. Last year, iPhone sales were Approximately worth 40Billion. (69% of 58B rev from apr 2015). This year, with 10m less volume, they're worth 32.5Billion. thats an 8 Billion drop in Revenue for 10m phones.
say this is a trend and the iPhone sells 10m less again next quarter (and assume same percentage without increases to other revenues). Revenues for the iPhone would drop further to 26 Billion (assuming 10m phones = 8b $). Assuming all other categories stays equal (which would be unlikely, but for hypotethical). Would further drop overall revenues down to 42B in revenues. With only 42B in revenues, That quarterly profit would be roughly 2-5Billion only.
I know this is a lot of assumption and analysis based on limited information. It's just me being an analyst. But it's not hard to see why, despite the size and profitability of Apple in the past 13 years, Wallstreet is questioning Apple's future. Wallstreet / investment is all about the future. Not the past. And there is doubts that Apple will be able to continue record revenue growth in mature markets. Especially, since IMHO, Apple has lost a lot of the uniqueness that set them ahead of everyone else. You could justify "apple tax" high margins when you were legitimately getting something that nobody else could equal. But now the competition has caught up, and in some places surpassed and providing much more compelling products.
Apple is NOT Doomed. But I think the days of Apple being #1 money making profit house and the leader in the smartphone wars is over. We're now in a mature marketplace for smartphones and rampant growth fo sales is likely ending for any established company.