Here's the info from the LTSS thread. There is no money in the LTSS budget for free receiver upgrades, so I wouldn't be surprised if LTSS ends at that date.
Shaw Direct will continue to operate the LTSS service for installed households at no charge, until at least August 31, 2019, which coincides with Shaw Direct’s current Licence period.
I took a quick look at the schedule and it looks like they are dropping at least some local SD OTA stations prior to that date, so it's possible that they overlooked LTSS and may have to adjust their schedule.
I'm not sure if the August 2019 date is a legal commitment. I recall that LTSS was supposed to run 5 years from the original date, so there may be some wiggle room.
Shaw Direct could continue LTSS and let users pay for their own 600 receivers.