One of the big problems with the recent Samsung (NASDAQOTH: SSNLF) Galaxy S5 launch is that, from day 1, it was already being made obsolete by the rumors of the imminent launches of more premium variants. This is in stark contrast to longtime competitor Apple (NASDAQ:AAPL) which launches its phone products on a fairly predictable yearly cadence, so customers never have to fear unwittingly buying a product that'll become obsolete in just a few months' time. 

This lack of Apple-like product launch predictability -- particularly after the Galaxy Tab Pro fiasco -- could be causing undue trepidation among Samsung's customer base and may be negatively impacting Galaxy S5 sales. 

The Galaxy S5 "Prime" rumors didn't help 
Ahead of the Galaxy S5 launch, there was rumor after rumor spread about the internal specifications, display resolution, and chassis material of that phone. Shortly after the S5 launched, a flurry of leaks surrounding a Galaxy S5 "Prime" -- which promised a higher resolution screen, faster internals, and a metal chassis -- began to hit the news en masse.

Of course, a phone with the rumored S5 "Prime" specifications (sans the metal chassis) was ultimately launched solely for the South Korean market (known as the Galaxy S5 LTE-Advanced). However, even before that phone went for sale, there were already rumblings of a premium Galaxy F phone.

The Galaxy F makes customers' brand-new Galaxy S5s seem obsolete
The alleged Galaxy F -- which rumors suggest will launch slightly ahead of the iPhone 6 -- is set to pack a 5.3-inch 2560x1440 display, a Qualcomm (NASDAQ:QCOM) Snapdragon 805, and a metal chassis. Given that customers have now been inundated with these leaks and rumors, can you blame them for being hesitant to buy the Galaxy S5, even though the S5 is widely regarded as the best Android phone on the market today? 

Now, that's not to suggest the Galaxy S5 isn't selling well -- it's holding its own against the various Android offerings according to Kantar Worldpanel ComTech -- but in some regions, like Great Britain, the freshly launched Galaxy S5 is still being outsold by Apple's relatively old iPhone 5c and iPhone 5s.

Could the Galaxy F help fend off the iPhone 6?
If Samsung really does launch a Galaxy F alongside the next generation Galaxy Note in a bid to fend off the next generation iPhones, the question will be whether this will be effective. Frankly, it's unlikely that people are buying iPhones over the Galaxy S5 because the iPhone has an aluminum chassis.

Whether Samsung sells a phone with a chassis made of metal, faux metal, plastic, or bamboo, the odds are good that most users are going to put that phone in a leather or plastic protective case anyway. The chassis/physical design of a phone, at least at this point given how mature this market is, is a second order effect to things like the strength of the marketing message, the performance, app ecosystem, and quality of the included software. 

Foolish bottom line
Though Samsung continues to be a mobile powerhouse and generates massive operating profit, it's starting to become clear that the race to try to displace Apple at the high end at all costs is taking its toll. Samsung is apparently shortening the life-cycles of its mobile devices and keeps trying to pack in feature after feature in a bid to compete.

While only time will tell, it's possible that the mere thought of the existence of a Galaxy F is taking an undue toll on Galaxy S5 sales. 

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.