They could also adopt an alphanumeric as a way of signifying the generation of the model. For example the new mid-2013 Nexus 7 could be called Nexus 7a, the 2014 model Nexus 7b etc. This would also kind of link in with the scheme for the alphabetic naming of the Android releases.
Cupcake > Donut > Eclair > Froyo > Gingerbread etc.
Alphanumeric naming would give them a scheme that could run until 2038 before running out of letters, retain a consistent root to the model names “Nexus 10″, “Nexus 4″ etc., would not require any major lengthening of the name, and it would be clear that Nexus 4b and Nexus 7a are from different generations of the Nexus brand in a way that is easier to grasp than even Samsung’s hugely successful Galaxy branding.
(For example a non-tech person completely unfamiliar with the Galaxy range could not tell from the name alone that Galaxy Note 2 and Galaxy S 3 belong to the same generation. They would maybe think instead that it should be the Galaxy S 2.)

That would be pretty good – turning the device names into brands and not rely on numbers to differentiate the different generations..

If current manufacturer update trends hold true though, there could be another dimension to the story.

Either one or both the next Nexus phone and/or small sized tab could change screen size from 4.xx” to 5″ or 7″ to 8″ respectively, which would actually mean the branding still won’t stick for the coming generation.

Either way, this is one of the times I could actually feel truly sorry for marketing departments.