The Nexus line of smartphones has been an important one for Google, maybe not in terms of sales figures, or even profit but, more so in terms of being able to show what Android is really capable of as an OS. Nexus devices have never been anything too special either, they're just another smartphone on the inside, sure, the specs are always quite good but these devices are by no means "specialty" by Google. Overall, you could basically describe the Nexus devices as just being a little different on the outside, with a different build of Android.
Of course, that's generalizing quite a lot there, and we all know that Nexus devices are so much more than that. They first started out as the device that was the reserve of the developer, the "hacker". Now though, they've become a consumer device, since the Galaxy Nexus they were easily purchased through an online storefront and they've become much more of a commercial release for Google. The same developer-friendly attitude prevails, with an unlockable bootloader and all devices being sold GSM-Unlocked.
We knew the Nexus 4 was coming, in fact, we knew pretty much everything about the device but it was "announced" by Google themselves. Many of you will remember the leaks that came weeks and months before the device was even acknowledged by Google as existing. Let's just say that it wasn't Google's best attempt at keeping a secret. This time around though, the Nexus 5 has pretty much been nothing more than fantasy. There's been no fantastical leaks, no blatant blunders by retail partners. Nothing.
This has led people to believe that there might not even be a next Nexus. Personally, I think that there is one coming, and it'll be here in the fall just as usual While the Google Editions of the Galaxy S 4 and HTC One are great, they're flawed in a couple of major ways. Nobody thinks of development, bootloaders and ROMs when they hear "HTC One" or "Galaxy S 4" - at least not the average consumer - they think instead of UltraPixels and features like Group Play or Air View. Google might be content with releasing a Nexus smartphone for mostly "the hell of it" but, they need to show the general consumer that Android is more than Samsung, HTC, Motorola, Sony et al - they need to show the world that Android is a pretty awesome OS and the best way to do that is to stand up and say, look at this awesome phone with the latest and BEST version of Android yet. When Google release a new Nexus - most commonly alongside a new version of Android - what they're really doing is saying: "Hey, come look at me! LOOK! This is why you want an Android phone over an iPhone, or a Windows Phone! This is why you want to use Google services more!".
When we talk about Nexus, we can't not talk about a new version of Android. Which has also been mysteriously missing as well. When asked when the next version of Android is coming, Google answer back with a quick "When it's ready". This is a sort of approach that we're not used to from Google, it's a fairly "grown up" answer to a question like that. We're so used to Google releasing a new version of Android once every few months that Google I/O is like mating season for Android fans.
With Android 4.0, Ice Cream Sandwich, Google announced a new approach to UI design and indeed, app design as well. Since then, we've seen little deviation from this blueprint and while 4.2 is a little different from 4.1 and 4.1 a little than 4.0, but overall things aren't all that dissimilar. I think this is a change that Matias Duarte pushed for when he was hired by the company shortly after the collapse of Palm. A solid, and stable platform is important to build a successful ecosystem around and it certainly helps when it comes to branding.
When will we see a new Nexus, and a new version of Android? When it's ready. When do I want to see a new Nexus or version of Android? When it's ready.