While these are valid concerns, Stripe transactions are still accepted and I'm sure there's a decent chunk of places using stripe. By the time chip is universal, I'm sure Square will have addressed this shortcoming. As for Interac, I'm presumig that the expansion to Canada will also include the Starbucks partnership, so I imagine it can't be far behind.
The regulatory environment is much different in Canada. The biggest thing I see here is the fact that a startup with significant attention and traction is entering our market. When they partnered with Starbucks, I was curious if that would mean they would provide coverage across North America and it definitely looks like they are. In the short term, I think Square Wallet is the key takeaway here. Mobile payments are gaining some serious steam and Square has a big chance to establish an early lead.