Hi Katherine,
There are plans to gradually reduce the age range of the 60+ Oyster as part of the funding settlement by the government. My understanding is that it will start later in six monthly chunks. Once you have the card you won’t lose it, but it will gradually get later and later. I don’t know when this is supposed to start, but the TfL website still says you can apply from two weeks before your 60th birthday, so it hasn’t changed yet. I got mine last December so I’m keenly keeping an eye on developments.