Based on past transitions, I highly doubt the receivers will be free. This years transition only affects HD signals as does next year. For the majority of non HD subs, there won't be any need to swap out equipment this year. I believe the only HD capable receiver not capable of MPEG-4 is the DSR530 as the DSR500 was already rendered obsolete when the HD channels transitioned from QPSK and 8PSK modulation. I can't imagine there are many active DSR530s out there since that receiver was plagued with software and hardware issues. I'd imagine most either upgraded to the DSR630 or switched providers.
There will probably be a small number of subs that need to go to a 600 series receiver and/or get an LNB upgrade to access the xKu signals from Anik G1. As for 2019, that will require an upgrade for any remaining subs on 300 and 400 series receivers. I'm guessing Shaw Direct will charge around $30 per receiver to upgrade and perhaps around $100 for the PVR. They will likely also charge for the xKu upgrade too.