On July 15, Green Mountain Coffee Roasters (GMCR.DL) filed to trademark "Karbon," which is a "machine for the production of cold water, soda, still, carbonated and sparkling beverages."

Investors immediately began to speculate that Green Mountain Coffee will be entering the single-serve cold beverage market space to compete with the likes of SodaStream International (SODA)

Can Green Mountain make a working product?
In order for customers to buy a Keurig Cold device, the company will have to model a machine off the success of its current Keurig machines in terms of timing, quality, and (more importantly) partners.

Green Mountain Coffee has licensing agreements with many well-known coffee makers to give its customers a wide variety of choices. While Green Mountain makes fantastic coffee, some consumers demand a "higher end" coffee experience to compliment the Keurig machine.

Green Mountain Coffee would likely consider Starbucks to be its most important "higher end" partner. Starbucks sells Keurig-licensed K-Cups, and has sold over one billion units since it entered the channel in 2012. According to management, K-Cup growth during the quarter was 42%!

Starbucks is to coffee as blank is to soft drinks
Starbucks is no doubt the king of coffee. But which company is the equivalent in cold carbonated beverages? More importantly, can Green Mountain Coffee land a similar partnership for Keurig Cold?

To answer the second question first, the answer is a "yes" based on comments stemming from a recent industry conference. This company, by the way, is The Coca-Cola Company (KO 0.31%)

During Beverage Digest's New York Conference, Coca-Cola's CEO Muhtar Kent said that single-serve dispensers are an "opportunity" rather than a "threat" to the industry. In addition, Kent noted that further innovation would determine the level of success for these single-serve dispensing systems.

If Green Mountain Coffee can deliver on its product and prove that it can replicate the current Keurig's success with cold beverages, a partnership with Coca-Cola is likely.

Would Coca-Cola really be interested?
The short answer at this point is a "yes."

Brian Kelley, Green Mountain Coffee's current CEO, worked five years at Coca-Cola, so there is little doubt that he knows what Coca-Cola wants to see in a product, and knows how to deliver it. 

Coca-Cola has been toying with the idea for several years through its "Freestyle" machine. The Freestyle machine is a touch screen machine that dispenses Coca-Cola drink products. Users select from mixtures of flavors of Coca-Cola branded products which are then individually dispensed. The machines use concentrated ingredients in the same way a Keurig Cold machine could work. The machines are available at Coca-Cola partnered restaurants such as Wendy's and Burger King.

"We've proven prelaunch and in-market that when a restaurant has Coca-Cola Freestyle, their traffic, incidence, and beverage servings grow anywhere from single to double digits," according to Coca-Cola's VP and general manager Jennifer Mann.

The success of Coca-Cola's Freestyle machine could hint that the company is open to partnering with Green Mountain to bring a similar device to the home market.

Fizzing out the competition
SodaStream already has a product on the market that makes cold carbonated beverages. It's devices are straightforward, easy to use, and most importantly work just fine in getting the job done.

Green Mountain Coffee must see that either the market is big enough for two players, or that it can come in and steal market share away.

SodaStream can be found at retailers like Target, Wal-Mart, and Bed Bath & Beyond. Green Mountain Coffee K-Cups are readily available at all channels, including grocery stores and convenience stores where SodaStream has no presence. Green Mountain Coffee has better distribution reach without any doubt.

SodaStream is also having trouble selling its current units and is heavily relying on promotional activity. For example, a "Mega Pack" starter kit bundle was being sold at Wal-Mart for $79 that included a $25 Wal-Mart gift card and a half dozen various flavors and accessories. The bundle also came packaged with two spare bottles and various other goodies.

SodaStream's recent promotional activities indicates a growing concern among investors that its devices are losing momentum. Green Mountain Coffee entering the space could spell trouble for SodaStream.

According to Fool analyst Jason Moser, all SodaStream has to do is have a very successful holiday season.  "If they can pull off a good holiday season, today's stock price will represent a very good opportunity."

SodaStream was recently downgraded by an analyst at Longbow from "Buy" to "Neutral" based on the research firms in-depth study of the company's performance during the recent shopping season.

The analyst noted that "Q4 results will trend toward the low end/below Street expectations. Promotions drove December survey results higher at Walmart and Bed Bath and Beyond, but light promotions at Costco and other retailers caused demand to suffer."

A carbonated conclusion
SodaStream had its 15 minutes of fame, but its time may be coming to an end. Declining demand and increased spending in marketing (including a Super Bowl commercial) could indicate that consumers are ready for something new. Consumers want something that can deliver a superior product through superior partnerships.

If Green Mountain Coffee develops a device that is truly free of a CO2 machine, it could indicate game over for SodaStream. Many Foolish readers are no doubt tired of paying around $20 every few months to refill the CO2 bottle!

Green Mountain Coffee is set to release its Keurig 2.0 device in 2014, so any Keurig Cold device is unlikely to be released in the near term.  As such, an investment on a successful Keurig Cold machine is a longer-term play.