it feels like at this point the only way she can get new songs into her set is to do covers. And then, when fans complain, she interprets that as "The fans only want the hits, they don't like new songs" rather than the real reality which is, 'the fans don't want to hear me sing other people's songs, they want to hear me sing MY OWN songs'...
Clearly she works to maintain her ability to sing her biggest hits to the degree she can, but just can't even sing so much of her own material any more...