It's not like summaries have to entirely replace whole books.

Personally I have a library on my kindle that's too much for me to read in full, considering I'm constantly adding to it. I read a lot of books but good summaries strike me as an improvement for the cases where I either never get to a book, or just read its first several chapters.

For the books I do fully read, summaries could make for nice reviews. With some further development, it seems this technology could turn the summaries into quiz questions, which would really help lock in long-term learning.