Reportedly, the changes are minor updates to keep things fresh. You should be fine studying even with old books.
I was in a similar circumstance 3 years ago, as CISSP changed from 10 to 8 domains. It was a much bigger change than today's. None of the third-party reference material had been reorganized, so it technically was outdated, yet it was the only thing available for my studies. Like you, I worried about the differences. Since the exam is more "conceptual" and less "detail", you probably will not even realize that there was a mismatch. I didn't.
If you feel that the books are simply reinforcing your on-the-job experience, you will likely do well. Problems come about when one tries to use the book(s) as substitute.
I have a different question but on the same topic. I have booked my exam for April, 11th but I wanted to make sure that the exam content does indeed change only from the 15th... I would not like to get a nasty surprise since it is quite close to the date!
Works the same way it did back in what... December and countless other times before hand. The format may change a bit but the overall questions and material does not. I have been quoted many times that security changes on the hour, day after day. Nothing new there.
Think of it this way. Your still testing on fairly "old" material as there is no way we could possibly test on the latest trends and functions within security itself. Then again, you can always wait for a horde of authors to pre-digest the material for you before sitting for the exam.
Either way its just an adjustment not a sea change.