On Apple's Q4 2015 earnings call today, CEO Tim Cook announced that it will partner with American Express to bring Apple Pay to Canada and Australia later this year, while Spain, Singapore, and Hong Kong will see a rollout in 2016. From the way Cook worded the announcement, it sounds like this will only be for "eligible American Express" customers in these countries, so we wouldn't expect a full rollout initially.
If the U.S. rollout of support over the last year is any indication, however, additional bank and card issuer support may expand rapidly over time. We don't have a specific timetable for when the mobile payments service will begin to land in Australia and Canada, but with only a couple of months left in 2015, it shouldn't be too far out.