Analysts are seemingly forever worried that this time, Apple (NASDAQ:AAPL) is going to miss sales projections on the iPhone, only to discover when it reports that it has handily beat them. The situation around the launches of its latest smartphone iterations was no different, and Apple proved the naysayers wrong once again.

The fiscal fourth-quarter report it delivered last month revealed that sales had increased across every product category, including the iPhone, which sold 46.7 million units. Moreover, after the iPhone 8 and 8 Plus went on sale in October, analysts wanted to hear what Apple would say about the coming quarter's revenue, which would give an insight into how sales were progressing. The company did not disappoint: It guided toward revenue of between $84 billion and $87 billion, well ahead of last year, and beating what Wall Street had forecast.

iPhone X

Image source: Apple.

Dialing up sales

The positive report indicates that iPhone 8 sales will be robust and even the expensive iPhone X will continue selling well. Analysts now see Apple continuing its hot streak; one suggested that between 25 million and 27 million iPhone X units will be produced in the quarter and as many as 24 million will be sold, with those figures surging by as much as 45% next quarter.

There's a good reason why Apple continues to be the most valuable brand in the world. According to Interbrand, which has been ranking corporate giants by calculation the values of their brands for 18 years, the Apple name is worth $184.1 billion, 3% higher than last year, and $42.5 billion more than second-place finisher Google.

Apple has sat atop the Interbrand list of best global brands since 2013 when it unseated Coca-Cola (NYSE:KO), which had reigned supreme for 13 consecutive years. At the time, Apple's brand valuation was just over $98 billion, meaning that in the ensuing four years, it has increased its value by a compounded rate of 17% annually.

Admittedly, a lot of those gains came in one gulp -- 2015, when its valuation surged 43%. For the past two years, the increase has been in the low-single-digit percentages. But there's good reason to expect Apple will remain the world's most valuable brand in the world for many years to come.

Rank Brand Brand Value % Change Y-Y
1 Apple $184.1 billion +3%
2 Google $141.7 billion +6%
3 Microsoft  $80.0 billion +10%
4 Coca-Cola $69.7 billion -5%
5  $64.8 billion +29%

Data source: Interbrand. Table by author.

A high hurdle to get over

First, while Alphabet's (NASDAQ:GOOG)(NASDAQ:GOOGL) Google had greater growth this year at 6%, it too has seen its growth rate slow.

As with so many growth-rate charts in business, scale at a certain point becomes an issue. The higher a company's brand valuation, the more difficult it becomes to continue achieving double-digit growth rates -- both because large, well-known companies increase their reputation with consumers and investors more slowly, and because the same value gain translates into a smaller percentage result.

Yet there's evidence Apple could achieve just that -- a double-digit-percentage brand value expansion -- despite its already-exceptional valuation.

A look at its recent pronouncements shows it's not resting on its laurels. In the course of just one week, it announced it was acquiring music tech company Shazam for an estimated $400 million, and was investing $390 million in laser chipmaker Finisar (NASDAQ:FNSR) for future orders, virtually precluding competitors like Samsung from being able to effectively compete.

Obviously, Google is not standing idly by. It's  also investing heavily in technologies like self-driving cars, Google TV, and its Chromebook and Chrome OS, not to mention the Android platform, which has a market share far exceeding that of Apple's iOS.

But at this point, the only vulnerability Apple's lead has is to itself. It might eventually stumble and lose its brand crown; it probably won't see another company surge ahead and take it.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.