DL will rebook on DL/AF, then on ST and only on other carriers as a last resort. Given the frequency of services on AF/DL as well as VS on the route, it seems unlikely that it would do so.

EC 261/2004 cancellation (delay) will cover the trip as it is operated by AF. Thus, depending on the reason for any cancellation or delay and its length, as well as when you are notified, there may be some cash in this.

Bottom line is that it isn't worth worrying about now. JFK-Western Europe has so many options to CDG and elsewhere connecting to CDG that it is highly unlikely you won't make it absent some major weather system. In that case, worrying about AF vs. VS is not the issue.