I assume Google wants to expand capability of the Chrome Browser instead of their operating system ChromeOS.
The disadvantage of Chrome OS is, that it is almost nothing without Internet connectivity. iThat may change with programs and or libraries, that are implemented as "Google Chrome Native Client".
Regarding these two points, I think it is the logical step for Google to establish Chrome OS with Chrome browser as a real platform. Why don't they just set up another operating system? Have a look at Apple, Linux and Microsoft: All programs that run exclusively on one platform, are a reason to stay with the OS of your choice. But installing a web browser, if you not already have, can not be considered as "leaving your OS". You can continue using your system of choice, and still be able to use Chromes features.
So I do think that client/server programming may change a bit, however rendering hypertext and processing user input on server-side will still be a thing we stay with a long time:
native client applications will not run in Firefox / IE which still have an immense market share together
processing user input can only reliably done on a server, there is no reason to trust data from a native client more than data entered in a standard HTML form or browser.
submitting user data to any kind of central storage will still take the need of verification and further processing (correcting, transforming, reporting)