Well, we expected the same gloom-and-doom for Amex Canada, when Amex USA introduced the one-welcome notes on their Personal cards in early 2015. Soon after in July 2015 Amex Canada added similar wording in the footnotes to our Personal card products but unlike in the US, Amex Canada never fully enforced it to the same degree, not even close. So we've been able to continue to repeat churn these Personal card products for the most part, though there have been many reports that fellow Canadians were denied the welcome bonus, and mostly by people who made the mistake of calling Amex to ask why they hadn't received the points yet, instead of waiting patiently for a scheduled sweep to re-conciliate the missing points (shout out to @
Preacher7 for notifying us with this tidbit, back then).
A few months later (still in 2015), Amex USA introduced similar wording into the Business card products' footnotes, and below the 49th they enforced them vigourously as well. Yet in Canada, we never saw those one-welcome notes on our Business card products (or correct me if I'm wrong, are they there now, finally?). Though occasionally, some people reported that Amex Canada informed them that they couldn't churn the Business cards, or that they couldn't have two concurrent Business card products and receive the welcome bonus again on the second card. Meanwhile, some of these people continued to get the bonus points anyways, after the next sweep, while a few did not (or so we assume, since they didn't come back to report with an update).
So, will a similar tool come to Canada? Let's hope not. And if it does, hopefully it's full of mis-diagnostics.