Not to shore if this has been covered already by anyone but here we go...
Now and then I receive an .AI or .EPS file from a Client/Printer which has been generated in a newer version of Illustrator which I cannot open.
Just drag it into Acrobat Pro, it will open and then you need to export it as required file. SIMPLE!
Note: Artwork should always be double checked but I haven't had an issue yet :P
Let me know if you have a better way than this (besides upgrading, lol).