Will be interesting to see what kind of "runway" they introduce; I hope they treat it like FFPs with their changes and give ample notice.
People will have made reservations in the coming 12 months based on their status at the time of stay - breakfast, lounge etc. If such benefits are not honoured, perhaps they would have looked elsewhere?

Without looking, I am sure there is something in the small print that would forfeit them of any responsibility but it would leave a bad feeling for many. They would be wise to ensure benefits are maintained for the remainder of ones card validity at the least; For those forecasting a future status (and booking) it is of course more complex and I think not much could be done (unless long runway).