When it comes to smartphones, the physical keyboard is -- for all practical purposes -- dead.

Apple has never offered a physical keyboard for the iPhone. Some Android vendors did for a time, but nearly all Android phone-makers have abandoned them. Samsung (NASDAQOTH:SSNLF) offered a variation of the original Galaxy S smartphone with a physical keyboard slider -- the Sprint exclusive Samsung Epic 4G -- but all subsequent flagship Galaxy models have sported a simplistic slate design.

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Samsung Epic 4G. Photo: Samsung

The Korean tech giant, however, is about to bring the physical keyboard back -- could this net its newest Galaxy handsets some additional sales?

A different kind of case
Samsung released two flagship phablets on August 21: the Galaxy Note 5 and Galaxy S6 Edge+. In a few weeks, owners will be able to purchase an unusual accessory -- a case with a built-in physical keyboard.

Admittedly, Samsung's keyboard case isn't the first such device -- third parties have been offering them for some time. Unfortunately, they're often poorly designed and implemented. Most of the ones for sale on Amazon garner relatively modest three-star reviews. 

Samsung's case has a few advantages over these third-party alternatives (though at $80, it is relatively expensive). Its phones can detect its presence and automatically adjust the user interface. It doesn't require power -- there's no battery to charge -- and it doesn't need to connect over Bluetooth. Instead, it simply sits on top of the screen, transferring physical button taps to the onscreen digital keyboard.

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Photo: Samsung

Unfortunately, that may not be enough. Mashable's Raymond Wong spent some time with Samsung's new case and found it underwhelming.

"I had a chance to try it out and I couldn't type 'Mashable.com' to save my life. The keys are flat and don't have the perfected arc curvature that BlackBerry(NASDAQ:BBRY) phone keyboards have...When I pressed the letter 'M', my thumb kept mashing the buttons around it and I don't even have big thumbs."

An untapped market?
Wong's impression may be unusual -- others could find Samsung's case more captivating. If they do, it could theoretically net Samsung some additional sales, as consumers who desire a physical keyboard have few alternatives.

The market demand for physical keyboards, however, appears relatively modest. After all, if there was still a healthy demand for them, it seems unlikely that Samsung, Motorola, and others would've abandoned them. The BlackBerry Classic, released earlier this year, received widespread praise for its keyboard (Engadget called it "all sorts of lovely"). Nevertheless, BlackBerry sold just 1.1 million smartphones in total last quarter -- almost a rounding error compared to the 47.5 million iPhones sold from the beginning of April to the end of June.

The original iPhone's digital keyboard was controversial when it was unveiled in 2007. Microsoft's then-CEO Steve Ballmer declared that the iPhone wouldn't "appeal to business customers because it doesn't have a keyboard." It was a fair prediction given the prevailing corporate obsession with BlackBerry devices at the time. Obviously, that wasn't the case. Today, the iPhone is the business phone of many -- 97% of the Fortune 500 companies use it in some capacity.

Samsung's case is an interesting experiment, but even if other reviewers are more kind, it doesn't seem likely to have much of an effect on sales. Other Samsung-exclusive features (such as Samsung Pay, rapid wireless charging, and the S6 Edge+'s curved screen) seem far more compelling.

Sam Mattera has no position in any stocks mentioned. The Motley Fool both recommends and owns shares of Amazon.com and Apple. The Motley Fool owns shares of Microsoft. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.