Let's do a small analysis of where Android's is at from Google's perspective. Right now, as much as Android fans like to boast how Android has 70-80% of the global smartphone market, it owns very little in terms of profit. Ask HTC, Motolora, and others. They'll tell you they're trying to compete, not to make money, but lose as little as possible. Most of the profit goes to Apple and then Samsung.
Having said that, a good number of these Android devices are priced competitively which explains Android's dominance. However, no much money to be made if any at all. Still, it's important for Google to go after developing markets like India with Android One (Google, Android Central). With Android One, Google is able to compete in the low-end market.
The reason is simple: Google has to fight with forked Android devices such as those from the Chinese. These entry-level phones will help make sure that Google apps and services continue to have a place in the mobile market. As more and more people in these markets can afford more expensive and mid-tier, even high-end, devices, that is where Google's Nexus comes in.
It's why this is a perfect time for Google to really go all out with the Nexus 6 and market it as the one true Android device that you want to own. Sure, it'll compete with some of its partners like Samsung and LG but Google does not really have a choice. Right now, high-end hardware is where the money is at.
Is this something Google is interested in? Android fans better hope so. It's main competitors are far more dangerous than ever before. The Chinese has the backing of their government and Google is locked out of China. Apple, Microsoft, Samung, and other Android device makers have no problem kow-towing to Beijing when it comes to censorship and adhering to anything that goes against freedom of all sort (sorry, had to take at least one jab against Beijing).
So, with the low to mid-end of the mobile market secured, that leaves the $650 32 GB Nexus 6 to try take more of the mobile market. It won't be easy but it's competely doable for Google and its vast resources.