Yup, that can happen, too. But generally, as the vendor, you need to be compatible with them, not they with you.
If the other way around with you as the customer, if you send your vendor something their older version of software can't open, they need to purchase a version that can.
It's the very rare client who will dumb down their documents for a vendor. They expect you to be able to work with them. Not the other way around.
Edit: I should add, this is the (mostly) normal sequence if the client it sending you their files. It can be completely the other way around. Such as, you're hired to build a 16 page mailing advertisement for a resort, or whatever. They hired you because they have neither the skills or software to do it. So anything you use, InDesign, Quark XPress, is up to you. That they can't open the completed docuement is irrelevant. They hired you to do the work.