Starting with Ubuntu 14.04 LTS next year, Canonical may switch Ubuntu Linux to a rolling-release model whereby package updates the bi-annual Long-Term Support releases would be the official images with rolling package updates for those releases.
In an "Ubuntu On Air" Hangout video, Canonical's Leann Ogasawara, their Kernel Team Manager, confirmed that the company is looking at moving to a rolling-release model with an Ubuntu 14.04 LTS target. It's not decided for sure that they will change distribution models, but Leann says, it's still in the cards of possibility happening.
With the change, Canonical would be looking to be more efficient and being of better quality. The usual six-month non-LTS releases would be eliminated.
One of the important prerequisites to switching models is ensuring that Canonical will be able to deal with the QA and that they will be able to ensure stability and reliability with pushing out new packages as they are released. Even right now with their fixed model, regressions are unfortunately not too uncommon.
Ogasawara's rolling-release comments can be found in the YouTube video below beginning at the 42 minute mark and lasting for a couple minutes.