Canada as a whole is not immune to a deteriorating credit outlook.  Trudeau's gamble on deficit spending may well stimulate the economy and reduce the deficit through higher revenues (without increases to tax rates), but if it fails, debt to GDP may further rise.  It's also entirely possible that recent economic growth would have happened anyway (e.g. lower dollar for exports, pent up demand for capital investment, real estate bubble, gradual adjustment to lower oil prices,etc.) such that the deficits are unnecessary and will only lead to higher taxes and the associated drag on the economy in the future.