I may be the only person reading this thread
but in case it's useful to others...
Eurostar Rebooking
My departure (1 Jan) is now within the strike waiver period. Although my train isn't cancelled, they're allowing free rebooking onto pretty much any Paris service. Any day in the next 180 days, including within the strike period. However:
Original route only - they won't let me change to Lille
One rebooking only - if I make a change today and subsequently find it doesn't connect with an SNCF service, tough
Must travel in the original direction Paris-London-Paris
The policy is not a published anywhere. I had to resort to DMs on twitter to get this information out of them.
I will leave it until the last possible minute, when I have some certainty about which SNCF services are running, (but will there be any availability on the Eurostar?) but I suspect I will fly this time and rebook Eurostar for a trip in the summer.