The SWISS press release says "Miles already earned with SWISS will retain their current validity".
I read this as to say that my miles are still valid for 3 years after accrual, even if I don't fly with BA within 12 months and would theoretically lose my Blue (or whatever) membership.
If EC doesn't change dramatically and award full mileage and tier points for all fares, I will burn all my miles with EC and switch over to either AA (for my travel with SWISS) or move to Lufthansa.