Do I still have to file a Canadian tax return the year after I've emigrated if I have no more Canadian income?

Generally, no, once you've genuinely ceased to be a Canadian resident and have no further Canadian-source income and no property left that would trigger a filing obligation, you typically don't need to keep filing an ordinary Canadian T1 return year after year the way a resident does. The obligation to file annually is tied to Canadian residency or to having Canadian-source income or specific reporting requirements, not to having once been a resident who has since genuinely left.

There are situations where filing still makes sense even without an obligation, or where an obligation persists despite having no ongoing Canadian income, for example, if you still receive any Canadian-source income subject to withholding, that withholding is often treated as your final tax on that income without a return being required, unless you're specifically electing under one of the mechanisms, like sections 216 or 217, that require filing to get a better result than the default withholding.

If your situation isn't a clean break, say, you still have some Canadian income, property, or a filed election from a prior year, checking your specific ongoing filing obligations with an advisor is worthwhile rather than assuming no return is ever needed again just because you've left.