There are other options as well, Telegram has voice calls now and Google Hangouts allows calls to US/Canadian phone numbers(PSTN). Good alternatives, but 'real' wi-fi calling provisioned by PM would be the best as it would allow for incoming/outgoing from your actual phone number, consistency, etc.
Wifi calling will save a lot of trouble for people with a low cellular coverage in their houses (like me).
You can call and message as you do normally and your iPhone will automatically use an available Wi-Fi network if it determines that you have low or no cellular coverage.
Wi-Fi Calling uses the same native dialer and contact list on your device as for cellular, for your convenience. No need to use any other app for communication.
Wi-Fi Calls use Internet data via your home Wi-Fi Service Provider at approximately 1MB/minute.
For PM customers like me, this would be a real help!
Even though PM is a lower brand by offering wifi calling (I hated it on rogers so never used it) and volte, they will only increase their presence and get more people over. These are standard features now that I am sure are easy to implement since they run on Telus. I'm sure it would only make PM better. PM can still offer these great services, what makes them no frills is the fact it's an online only service and you can't talk to anyone. There is no overhead.
In Toronto this would be a great feature for use when waiting for the subway. It would also compete with Freedom Mobile which has mini cell towers in some of the stations.