On the migrations, the customer, even if they own the old 301, will be moved to a leased receiver of the newer variety (311, or for most, a 211 series). The customer can ask about moving to a purchased 311 or 211. Obviously a purchased receiver does not create a 24 month commit, but the customer would also be required to pay something for the new receiver. It's not done via the RA process, it's done via the Change Receiver program (formerly known as DIU, Dish'n it Up). When the receiver change is required, there is no cost or obligation for the customer, even for a leased receiver, other than the customer hearing the leased receiver disclosure, that they will have to return the new receiver (not the old one) if the customer were to cancel their service.
I'm not saying it's a good thing or a bad thing, I'm sure it could be argued that a purchased 301 (or older) should be replaced with a purchased 311 or 211. I'd be more inclined to agree on the 311, but the 211 series is a more expensive line.
Oh, also...LOL...don't try to buy a 311 from Dish right now. The cost is usually $200, where a purchased 211-series is $99. You can see that Dish is obviously trying to discourage the purchase of a 311.