Would the ruling on citizens living in foreign countries would apply to those by-elections (context: a Court ruled than removing the right of vote to citizens living in foreign coutries since more than 5 years was unconstitionnal. That would lead to one million of persons possibly added on rolls.)?
I am guessing in this case they would go by the last riding one lived in when they left Canada. My question is what about those who have never lived in Canada but got citizenship by being born to a Canadian born parent, what happens then?
No clue. Most likely government or Elections Canada will have to find a solution (or appeal, as the judge refused to grant them a stay).
One solution might be to have overseas constituencies like France and Italy do that way you wouldn't have the issue of people voting in ridings they no longer live in, but they will still be able to exercise their right to vote.
In that case, you have members who don't even live in the country for which they're parliamentarians. That strikes me as undesirable.