If the British monarchy is abolished while the present monarch is alive, there will never be a time when “the British Queen” dies.
There have been no events within my lifetime to support this theory.
Her biological parents died. The evidence is overwhelming that she shares the trait of old age mortality with (so far) all the other humans that have ever existed.
I can think of about 7.8 billion examples of people who demonstrably exist and who have not yet died. Our best guess is that comprises around 5% of all humans who have been born.