Google's solution is Project Ara...and it's coming inside 2015.
The concept is a simple one –– you buy a basic model Ara phone and all the bits can be pulled off and swapped as you see fit. Fancy a more powerful camera module? You'll be able to buy one through Google's dedicated store - a treasure trove of hardware modules populated by components made by third-party manufacturers, from the likes of Samsung and its ilk, right down to little independent devs working out of their basements - just like Google Play for apps, in fact. The same will be true of many other components, including things like memory, display panels, physical keyboards, sensors and scanners, ports, modems and wireless modules, and much, much more.
The Verge got a look at some Ara prototypes at Google HQ. Here's an extract from their report: "This very early version of the phone we played was functional, although we weren't allowed to turn it on and use it, in part because the touch features aren't up and running, Google said. The company showed it booting up on stage, but not working. The hardware itself feels very solid, thanks to its aluminum and steel frame, which looks like a ribcage when all the modules are popped out. The modules on the other hand feel light and plasticky, and made holding the phone feel a bit strange. If you're used to the smooth corners you'd find on most smartphones, the ribbed channels on the Spiral 2 feel bizarre. Nothing rattled or slid out while we were playing around with it, though it's hard to tell how it will really work without the magnets."
More recently, Google provided an update about what it has been up to since announcing some prior details about Ara at I/O 2014. The Big G has been busy working with Marvell and NVIDIA in order to get some reference CPUs made for Ara. Below is an extract from Google’s G+ update on the subject and what progress has been made.
“For the AP modules, we have been working with our friends at Marvell and NVIDIA to create two separate reference designs and form factor module prototypes around their PXA1928 and Tegra K1 processors, respectively, using a Toshiba UniPro bridge ASIC to connect to the on-devicenetwork. You can anticipate seeing these as part of the reference designs in our upcoming MDK v0.20 release. (The Rockchip AP with native UniPro that we blogged about previously is coming along nicely and will be ready in time for our Spiral 3 prototype in the Spring.),” said Google in a post on Google+.