None of us will be able to give you conclusive, definitive advice of what will happen.
I would strongly advise you
to ring Flying Blue and discuss the matter with an FB agent. In view of
FB's published statement that miles will not expire in 2020 for all members - although this does not specifically relate to your specific case (in which, indeed, the refunded miles should automatically expire given their age), I think you stand a very good chance of having FB prevent them from expiring, AS AN EXCEPTION given the circumstances,
but you will have to work with FB to make sure that this happens as there is every chance that otherwise they will be lost for good.
You could perhaps work with the FB agent on the phone to instantly change your tickets - which may actually be the best thing to do. Just having your miles returned to your account is one thing, but it will be unclear when they would then expire - so I would advise you to "use" them again instantly.
Of course, now that we have variable pricing it may arise that you won't have enough miles to book the same trip again, but you can probably come up with some other use of them, working with the phone agent to check dates. It would help if you have a look beforehand on the Flying Blue booking tool and already have zeroed in on particular flights/dates.
I can't guarantee that any of this will work out - but to get the best outcome for yourself, I can't see any other option but to call Flying Blue.
I would not rely on adding "new" earned miles to your account, or acquiring a credit card - the system should have been robustly designed to notice that there is a separate pot of "dead" miles which are not eligible for this sort of prolongation. (The "dead" miles may have already been taken, or may never even be returned to your balance, meaning that buying a flight/credit card is almost certainly pointless as it may not have the effect you desire)
And please do come back and let us know your experiences.
Good luck!
Originally Posted by
MrMoonlight
How about if I purchase a cheap flight on Delta for a trip I may or may not take and provide my Flying Blue number to keep my account active?
Your FB account is currently active. You do not make an account active by buying a flight.
Note that merely buying a flight does nothing to your mileage balance lifetime. it is only when you take that flight, and new FB miles are added to your existing balance, that that entire balance has its expiry dated updated.
Buying a Delta flight now for travel on any date in the future won't save your miles. When these refunded FB miles hit your account, they are "dead" miles, and instantly expire. By the time any new FB miles from a new Delta flight hit your account, the account already has a zero balance. New miles cannot extend the lifetime of "old" refunded miles. That's why I advise you to talk to FB to see if they will stretch the rules for you. You will need manual intervention in this case, I believe. You cannot just rely on the automated system (whether by buying/taking a new earning flight, or acquiring a credit card)