Samsung's Gear S2. Photo: Samsung.

Samsung (NASDAQOTH: SSNLF) plans to launch its seventh wearable and sixth smartwatch next month: the Gear S2. It features an innovative round design and rotating bezel, two aspects that have earned it high praise in most hands-on previews. Samsung's Gear S2 could succeed where its predecessors failed, and stand out as the most compelling alternative to the Apple (AAPL 0.44%) Watch.

Yet it may be Samsung's partner, Google (GOOG 1.09%) (GOOGL 1.14%), that determines whether the device succeeds or fails.

Samsung's missing partner
The Gear S2 features many of Samsung's own apps (Samsung Pay, Milk Music, SmartThings), but is also capable of running apps from third parties. The Korean tech giant has said that the watch will support at least 1,000 different apps at launch, including Nike+, The Wall Street Journal, and Line. During its unveiling, Samsung showed a slide highlighting these and other partners of note.

There was, however, one glaring absence: Google was nowhere to be found. The search giant makes many of the most useful and most popular mobile apps in the world, including Gmail, Google Now, and Google Maps. While Google's presence hasn't been ruled out entirely, it seems likely that if it intended to support the watch, Samsung would've highlighted Google's apps at the Gear S2's unveiling.

Samsung takes on Android Wear
It wouldn't be surprising if Google declined to support the Gear S2. Samsung's original Galaxy Gear ran a modified version of Google's Android operating system, and its Gear Live was powered by Android Wear, but all of Samsung's other smartwatches, including the Gear S2, run its own proprietary operating system, Tizen. Google has not released any apps for Samsung's other Tizen watches, and the search giant has a vested interest in seeing the platform fail.

Samsung continues to use Android for its Galaxy smartphones, but did release a Tizen phone earlier this year and has hinted in the past that more could be forthcoming. Samsung's relative importance has faded as other Android OEMs have emerged, but it's still the largest smartphone vendor in the world. According to OpenSignal, nearly 40% of the Android devices currently in use were made by Samsung. It's unlikely, but if Tizen were to emerge as a legitimate mobile platform, it could undermine Android's smartphone success.

More threatening is the Gear S2's potential to disrupt Android Wear, Google's own upstart smartwatch platform. Android Wear is just over a year old, and remains in its infancy, but Google has already succeeded in capturing the interest of tens of thousands of developers and attracting a wide variety of hardware partners. Some will see the Gear S2 as Samsung's answer to the Apple Watch, but in truth, the devices will serve two different markets.

The Apple Watch requires the use of an iPhone -- if you own an Android phone, Apple Watch is no use to you. The same is true for the Gear S2: iPhone owners cannot take advantage of Samsung's wearable. The Gear S2 requires a relatively modern Android phone -- it doesn't have to be made by Samsung, but it must be powered by Google's Android operating system.

Google's Android Wear, in contrast, does support the iPhone, but only in a very limited sense. Some iPhone buyers could opt for a cheap Android Wear watch (perhaps as an alternative to a dedicated fitness tracker), but to truly taking advantage of the platform you need an Android phone. There are billions of Android users in the world, but the Gear S2 will be competing directly with Android Wear for a limited number of wrists.

A lack of Google apps could doom the Gear S2
Without any Google apps, Samsung's Gear S2 could be dead on arrival, regardless of its great design or unique functionality. There are alternatives, but without Google Maps, Google Now, or Gmail, expect many would-be buyers to turn to Android Wear instead.