It is really annoying to work with Premiere pro, dealing with clients who doesn't always have the newest Version. The changes you make with the upgrades are not that huge, so I don't See the reason to make it impossible to work with a slightly older Version, importier a file from a neuer one. I appreciate the whole adobe suite very much but this is really a pain, since the updates are coming more frequently
while this is a rather critical and large change to the way the application works and will take some time to be implemented, we'll definitely put this under consideration.
There's more than one solution to this problem, though.
A good short term opportunity is to use the parallel install feature in the creative cloud application. It should help to at least take away some of the issues working with people on a different version of the application.