She is still doing some of her public duties, @lameasahorse - but is delegating others, which is sensible because of her age and mobility issues. And it is giving Charles time to transition into the role, rather than having it thrust on him all at once (whether because then Queen has died or because she has abdicated/retired).
Charles might not think it’s the best thing, of course - he has waited a long time for the top job, and is already past retirement age himself. And it might have been better for her and Prince Philip, if she had been less dedicated to doing her duty for the whole of her life, and had abdicated a few years ago, so they could have enjoyed retirement together.