The details are pretty thin on the prototypes, but videos from NotebookCheck show the laptop display growing from about 12 inches to 16.

Lenovo/IBM do have a history of expandable laptops, with the famous butterfly keyboard Thinkpad. How cool would be be to have that keyboard plus a widescreen rollable display?

https://www.youtube.com/watch?v=-JyXbWHbvis
https://www.youtube.com/watch?v=hwZ9klMWSLU