That you can now stream Photoshop to Chromebooks it's not just not a big win for Google, but to GNU/Linux at large. It means that now the idea that Photoshop could become available in other distros is not really all that crazy.
That Adobe finally decided to bring the flagship photo editing software to GNU/Linux via Chromebooks is a big thing since it takes away another reason for not coming to GNU/Linux. Most importantly, if it does well on Chromebooks Adobe might have an incentive to bring Photoshop some of the other major GNU/Linux distros like Ubuntu or OpenSUSE.
If more people start moving to use Photoshop on GNU/Linux, it might the spark that GNU/Linux has been looking to really become a mainstream OS and not just something used a few. There will be a bigger set of people that now will be able to see, and use, a GNU/Linux distro as a viable option to use on daily basis to work with.
I still temper my optimism with a grain of salt. It's a great first step, but there still a long road ahead to be called a success since there still much that could give Adobe cold feet. Yet, a very promising news and the kind that give me hope that GNU/Linux might have a break on the desktop.