Yes, physical books are still avalible to check out and borrow. Becasae books will be stored at a warehouse, you can request the book online or in a branch and pick it up at any location.
The idea is to encourage users to get the books in digital form on a tablet. If a book is not avalible in digital form it can be reqested and scanned within a few minutes and avalible to the patron the same day.
Many library users could never imagine not having access to physical books, and feel an emotional and physical connection to them.
It would be unwise to remove physical books from public libraries altogether. The content within a physical book is identical to that of the same digital book; only the delivery method is different.
Over time the advantages of scanning books and making them available in digital form will outweigh the demand for paper books. This is already apparent with increasing demand for tablet devices and e-readers, with tablet adoption almost doubling from 2012 to 2013. The younger generations are shifting rapidly towards digital forms of reading and information consumption. Eventually paper books will become a novelty like that of vinyl records compared to digital music.
As it stands today library US collections are made up of approximately 87% physical collections (PDF Source), most of which are books and only 13% digital collections. The goal for the tablet library should be maintaining existing physical book numbers and continually adding digital books. Over the years and coming decades the numbers should flip and the percentage of physical books should be less compared to what is available digitally.
This shift to the digital is inevitable; whether libraries are involved in this shift will determine how the new public library is defined. It is important for the public library system to understand this shift to the digital. If the public library system does not get on board with this digital shift it will eventually get left behind.
The tablet library should embrace this digital shift and be on the forefront of digital information technology.