Depending on what you mean by the Kensal Rise Library books, I may know the answer or not. If you mean the Council owned books from when it was a library, the answer is that they were crated up and moved to Willesden Green Library, and they are now in circulation among Brent Libraries and of course library users.
The second sense that I don't know the answer to is the fate of the "pop up" library books that appeared on the site shortly afterward. The pop up library appeared to be an initiative by the Friends of Kensal Rise Library (FKRL), although this was subsequently denied any involvement when they were asked to remove it. It was taken down by agents of All Souls College in January 2014 when it was due to be passed to the new owner as a vacant possession.
There were complaints at the time of the books being dumped on the pavement, and exposed to the elements. Given that they had already spent a long period in an unheated structure half exposed to the elements and to insect life, I imagine that they were probably not in that great a state anyway, but they were taken away towards the middle of February. I understand that they were stored somewhere in the Bridge Park Sports Centre. I wonder where they now are, and what their eventual fate will be?