"Is Office 365 required to run Office 2013?
No. You will still be able to purchase any Office 2013 edition with a perpetual license that doesn’t require any ongoing subscription fees. This version can be combined with a free Microsoft Account (aka Windows Live account) to allow online document storage and sharing."
http://www.zdnet.com/office-2013-editions-at-a-glance-and-fa...
Note: actually, iWork doesn't come with every new Mac, but I felt the joke irresistible.
PowerPoint is the main issue. I've made a lot of animations for my courses that I'll have to remake from scratch if I switch programs.
(that said, I don't love LibreOffice and I don't know of any truly solid presentation solutions that are open, cheap, multiplatform and reasonably future-proof. I'm a coder so I've ended up in HTML5 + Sublime Text for my slides, but tooling for this option is rather limited)
I'd be interested in seeing recommendations for alternatives.