I can confirm this is true, though the date this is to he brought into force is yet to be confirmed. It had been planned to become obsolete on the 1st of January 2015 but that has now been delayed and all drivers, both learners and those passed, should remain in possession of both parts of the licence.
Currently, when a learner is presented to a theory or practical test they must show both the card and paper part of their driving license. The information is largely the same on both, bar the presence of the photo and endorsements on each. I believe that with modern technology a lot of the information will be kept on computer databases and the photocard will be used like an ID card in the future, to represent an individual, with most of the important information being stored on a central database accessible through the DVLA. The paper counterpart appears to have been left behind somewhat. To me, it makes a lot of sense. It is not really an item you can or even should keep on your person, and is just another document that will be easily lost at home. In this modern paperless world we live in I think it makes complete sense.
In summary, until official word comes that the item is completely obsolete then keep hold of your paper license, learners will be refused the opportunity to take their test if they do not have it on both their theory and practical tests. If you have lost your paper counterpart too, it is still a necessary legal document and they are still providing replacements until further notice on the impending changes.
It is also worth mentioning that if you have picked up any endorsements or penalty points it it's paramount that you make sure your counterpart is up to date with the DVLA and cooperate with them fully. It is also advised that your name and address are up to date on both parts of the licence.