http://www.telegraph.co.uk/travel/news/ryanair-cuts-carry-on-luggage-allowance/
we've already done this
https://community.ricksteves.com/travel-forum/general-europe/ryanair-luggage-changes
That's 13.7" x 7.87" x 7.87" Or smaller than a RS Civita bag.
I have to wonder if they are taking a page from the Spirit airlines playbook.