I have been in the same situation - I booked award seats from RDU-FCO through CDG on AF in J using VS miles, with the return happening on Thursday, April 5. A couple of weeks ago I got a notification from Air France that my flight had been canceled. I called VS support and got a super-helpful agent who called Air France for me and originally got us rebooked home FCO-CDG-DTW-RDU, with DL metal across the Atlantic. That stuck for about a week, then I got an email from VS support who said that my flight had been canceled and did I have any flexibility on the return. I emailed them back and they were able to get us on the CDG-RDU return flight the next day (April 6). Hopefully this will stick - but this whole process has been pretty annoying/stressful. I will say kudos to the VS agents who have been nothing but helpful and proactive.