In a move that was expected by some and feared by others, Amazon today announced its own AWS Storage Gateway, which immediately calls into question the long-term validity of the business models for standalone cloud gateway vendors.

Following the implosion of Cirtas in April of last year, cloud gateway vendors have basically positioned themselves as “on ramps” from a customer data center to the actual cloud providers like Amazon, Azure, Nirvanix and Rackspace. With Amazon now offering its own cloud gateway, this calls into question the need for the middlemen who have been pushing their wares as a means of getting access to the Amazon cloud.

By cutting out the middlemen, Amazon could single handedly accelerate the demise of the standalone cloud gateway market. Sure, today the standalone vendors will cry out in protest that they offer “advanced” features that Amazon doesn’t have yet and that Amazon is still in beta mode—but the looming threat is irreversible: Amazon now has a platform that it can build additional functionality on to—and it will—rapidly

While they may have snapshots, encryption and cached volumes today, look for Amazon to add incremental functionality like data deduplication, file locking, and multi-site file sharing in the coming months.

For cloud gateway startups that have made broad public claims about their products’ ability to give customers superior access to AWS, today’s news doesn’t exactly fortify their business strategies. After all, Amazon can make their gateway work better with their own cloud than anyone else can—they do own it from soup to nuts, you know.

What does this mean for startups like Ctera, Nasuni, Panzura, TwinStrata, StorSimple and Riverbed’s Whitewater group?

VCs who invested in standalone cloud gateway vendors should definitely be concerned right about now.