Answering the question in the thread title: if you have a purchased one, you can still activate it. Good luck getting Dish to send you a replacement if yours fails, though. They will probably try to get you to upgrade to some kind of Hopper system, or at least Wally.
No, you do not have to send them back. You can fill in the blank before the "22K" above (222, 622, 722, 922) (with or without the K, as the case may be) and the answer is still the same. (For that matter, the same thing applies to 322 and 522, but those ones are not ViP.)
They are considered LEGACY. However, if they do activate it, or if you currently have one activated, then should it require a replacement, they will replace with a like model--that you may not like, but they would certainly invite you to upgrade.