you would retire on RRSP + CPP (very small) + whatever you currently have in your 401k + whatever you have in retirement savings from any other country(ies) you have lived in.

That said, depending on your age, with a max RRSP contribution of 27k, if you can contribute the max for 20yrs, you should have enough to retire on RRSP alone, assuming reasonable retirement living.

Assuming you contribute $27230/yr for 20yrs, and manage to get 5% growth on that account each year, you would end up with about $1m in the RRSP. It all depends on how much time you have to grow the account I guess.