So Google didn't announce the follow up of the Nexus 4, which many were expecting to see at the Google I/O event. No Nexus 5 then although one might wonder whether the special edition Galaxy S4 that Hugo Barra announced was not just that.
The very reason, one might posit, as to why the Nexus range was originally unveiled by Google was to make sure that its partners produce competitive hardware of the highest quality. The Nexus One was one of these, followed by the Nexus S, the Galaxy Nexus and the Nexus 4.
Once these conditions are met, there shouldn't be any more impetus for having a dedicated smartphone bearing the Nexus moniker. The Galaxy S4, it seems, hit the right spot as Barra went on record saying "Google's take on Android - and it feels really awesome on the Galaxy S4".
There's also the fact that Samsung's newest top of the range smartphone has a 5in display diagonal, which makes it the ideal candidate for the Nexus moniker.
In the end though, the Nexus spirit hinges primarily on the fact that the OS should be as unbridled as possible. Which is ironic given that Samsung's been betting very heavily on differentiating itself from its rivals through software USPs (Smart Stay, TouchWiz, S Health, AirView, Knox etc).
Samsung will unlikely change its marketing strategy even if the Samsung Galaxy S4 Google Edition becomes a massive commercial hit as it would serve its rivals more than itself.