What are we supposed to do if our old MacBook only has lion?
Go down to the Apple store and fork over $2000 for a new one?
(mandatory Crapple pic) 
What are we supposed to do if our old MacBook only has lion?
You might try one of the previous versions of Linux Mint with the Cinnamon or Gnome desktop. Depending upon how much memory your machine has you might like that OS much better. I believe ver13 LTS (Long Term Support) might be compatible but you should probably look for yourself before committing.
What are we supposed to do if our old MacBook only has lion?
Go down to the Apple store and fork over $2000 for a new one?
(mandatory Crapple pic)
Can your model upgrade to at least Mountain Lion?
I can understand that it might not -- I have a much-beloved old 2007 white 13" MacBook that will only go as far as Lion (it's currently at a release before that, Snow Leopard). Like some of the other posters, I've considered putting some flavor of Linux on it, but frankly it works fine with the old OS X release, and I can't think of any good reason to lose an OS X platform, even an old one, given that I've got plenty of Linux platforms already. I guess I'll upgrade it to 10.7, but that's the end of the Lion...
Damn that Apple hardware that keeps working 8+ years. :-) *sigh*
Update to Yosemite. It doesn’t cost anything.