When Google showed the Galaxy S4 Nexus at I/O, the move kind of surprised everyone, and it made people wonder about what Google intends to do with the Nexus program in the future, and if there will be an HTC One Nexus, too.
This is actually something I've been wishing Google would do for a long time. Maybe not exactly the idea that they should take existing models from the market and turn them into Nexus devices, but the idea that they should allow a lot more OEM's to release Nexus devices at the same time during the year.
Pretty much all manufacturers are making their own skins and interfaces on top of the core Android these days, and they are probably not going to stop doing that anytime soon, unless we as a community show them that we prefer stock Android devices, and a unified Android experience across all devices.
Some may say that making their own skins is the way only for manufacturers to differentiate. I say that allowing manufacturers to make their own UI's has not only created some terrible experiences out there that people now associate with Android, but it has also made manufacturers very lazy. Why bother creating much better and unique hardware, when you can just change up the software and leave the hardware mostly the same?
Manufacturers have forgotten that they are manufacturers, and that as manufacturers they really should be differentiating through hardware, not software, because that is and should be their expertise - not software.
But it's going to be very hard to convince them to stop using skins. However, Google could convince them to release some of their phones as Nexus devices, while following Google's strict guidelines. This could create at least a sub-group of Android devices that get updates on time and for at least a year and a half (or 3 new versions of Android, on top of the brand new one they come with). These Nexus devices would be launched in the same way as Chromebooks are being launched. Google alone controls the software Chromebooks, and can update the machines every couple of months, while a lot of manufacturers can make these machines.
If Google were to do this with Nexus devices, too, and if these devices became increasingly more popular as a sub-market inside the whole Android market, then eventually we might wake up that most people buy "Nexus" devices, instead of regular "Android" devices that have all sorts of skins on them. People like familiarity, and it's actually one of the main reasons why Windows has been so successful over the decades, and why so many are annoyed with the Windows 8 interface now.
By having the majority of Android devices as Nexus devices, Google would have full control over the majority of Android devices on the market, and they'd be able to upgrade them often, and at the same time. No OEM's and no carriers involved in the upgrading process. That would significantly decrease fragmentation, and it would help both users and developers, and of course, Google.