There is no way this catches up to e-transfer in popularity. Everyone in Canada knows about venmo and cashapp and the various other scam versions of e-transfers that people are forced to use in America and they laugh at them for it.
E-transfers are literally the best part about Canadian banking.
They don't need to catch up to e-Transfers to be successful. I'm not sure what their numbers but if they manage to be the app of choice for university students and young adults alone, it would be a massive win for them. I know people who have started to pay their rent using WS Cash, and I'm sure when they graduate they'd like to continue doing so. There's also the Cash Card directly tied to this account, which they get transaction fees from, as well as associated WS Trade/Invest.
I'm not trying to be a shill, I personally wouldn't invest in WS since I think they're incredibly overvalued. But E-Transfer is very dated and has a lot of problems, and there is potential for a competitor to come up and replace it.
E-transfers are literally the best part about Canadian banking.