Google has begun working on its next-generation VP10 codec, as shown by some recent commits to the public libvpx repository, where Google adds new code to its open source VP9 codec.
Google got the VP8 codec with the acquisition of On2 Technologies back in 2010, which it later open sourced. However, VP8 was already years behind in development compared to the standard proprietary H.264 codec. By the time VP8 became about as good, H.264 was already ubiquitous, not just in software, but also in hardware.
VP9 also arrived a little late compared to the proprietary HEVC, but not nearly as much as VP8 did. Google uses VP9 for its YouTube service now, and some chip makers have also adopted VP9 decoding in hardware. HEVC is a little further ahead in hardware support, but it's also rather far from being ubiquitous, which means most people can't get efficient 4k video streaming just yet.
HEVC also seems to have increasingly more patent issues tied to it lately. This could not only hinder its adoption, but may even kill it for applications and services that are free or open source, at least according to Cisco.
With the IETF working on a next-generation open source and royalty-free standard called NETVC, it seems like the right time for Google to push its own next-generation codec as well, perhaps as a candidate for NETVC. Mozilla and Xiph's Daala video codec, as well as Cisco's recently announced Thor, are already part of the candidate list.
Google hasn't yet said anything about VP10 becoming an NETVC candidate as well, but it's still very early in its development life. Ultimately, the IETF may not choose one of the multiple candidates to become NETVC, but could combine the best parts of all of them to create one great next-generation codec.
Having multiple candidates that all strive to be royalty-free and patent unencumbered should also greatly reduce the chance of using code that infringes on someone else’s patents. The IETF could choose the parts from the candidates that are least likely to be found infringing, in order to create a legally untouchable codec that anyone can freely use with no restrictions.