It is a really good question, because risks exist in any type of voting. Just like in Canada with voters who reside in Canada, some will vote and some will decide not to vote, especially people living abroad, as there are very different circumstances.
For example, if you are a student or are residing abroad temporarily, you might be much more connected to the political process and be much more willing to cast a ballot. Obviously, some Canadians have decided to permanently leave Canada, and they are perhaps not thinking of coming back and have started to live somewhere else. For them, voting might not be top of mind because they might be more engaged in their new country.
I think a portion of the population living abroad will always simply decide not to vote. I would say there is a very good chance that a big chunk of the population living abroad will simply decide not to vote, and that is their right.
In terms of risks, this is something that all modern democracies have to deal with. Is there a risk, for example, if we include being able to print a ballot instead of having it mailed? Are there some electronic risks? I am sure these kinds of things can be mediated through the process.
I don't necessarily see any sort of risk in trying to switch the location of where to vote, because it is tied to your last riding. Things like that are already prevented by the system itself, so I don't foresee any major risks, but we need to acknowledge that not every Canadian abroad will choose to vote.