JAPANESE magazine Young Machine believe that the Suzuki MotoGP machine spied in testing could be based around the next generation GSX-R1000.
This is purely speculation, but there is some smart thinking behind the theory as Dorna have been making a lot of noise about moving the prototype machines towards CRT. With this in mind it would make sense for Suzuki to start developing their GP racer based on an all-new 2014-spec GSX-R1000 engine.
If there is the planned introduction of a stock ECU and rev limit, a GSX-R based engine shouldn't give away a huge power deficit to the full-on prototypes and it would work nicely as a marketing tool for the production bike.
The 1000cc GSV-R was spied in testing at Sugo, Japan earlier this week and trackside sources stated that the bike had an engine note similar to the Yamaha YZR-M1, and therefore could be using a cross-plane crank. This is something that Suzuki could have committed to in 2009 when the YZF-R1 was released and around the time when they would have begun development on the 2014 GSX-R.
On a side note, it's interesting to note that the very first generation GSX-R1000 was developed with half an eye on MotoGP. Even though they eventually went with a full prototype V4, the original GSX-R1000's capacity can't have been 990cc by accident...
Despite the criticisms for CRT tainting the pure-bred prototype nature of MotoGP the adoption of this model does provide an interesting outlook for the series, as shown by the Aprilia bikes on the grid at the moment, it could see manufacturers bringing forward over-the-counter GP bikes like the RGs and TZs from the late 70s/early 80s.