I checked the new T+Cs. There are some peculiarities:

1.2.9 includes: For Ivory Members, Award Miles are valid for 20 months. Only accrual on flights ... or any other activity designed as extending in the FB Communication, is considered as an extending activity. (My bolding)

Does this mean we can look forward to using such 'other activity'? I won't be holding my breath.

And

It is up to the Member to check the expiration date of his Miles.

OK, let's check online, like with normal FF programmes. Er, no. This is not possible. The expiry date not shown on the website and only six months' activity is shown, so checking back beyond six months is not possible online.

1.2.10 After a period of 6 years of no accrual of Award Miles by a
Member, the Company reserves the right to unilaterally terminate
membership.

So we can remain a member with a zero balance, presumably. I wonder what the benefits are of Ivory membership with no miles.