She reportedly has Covid now so whether she gets to 99, or even to whatever jubilee celebration is meant to be next year [saw several UK posters on Reddit possibly lamenting the loss of the bank holiday it would bring if she was no longer Queen for whatever reason], is up for debate.

She could die.

She could survive, yet step down after the attempt on her life leaves her scarred her health worsens.

She could go on until after the jubilee then step down after that as it would be a significant point to cap things.

Or she could reveal herself as an immortal lizard, tear off her skin mask, and enact the Eternal Empire that rises up from the bowels of the planet.

For bonus points, for you mostly, it turns out the female lizards reproduce through Parthenogenesis as can happen in Komodo dragons. Although due to haploid genetics all eggs that hatch this way are male [Z] as parthenogenic female eggs [W] fail to mature in Komodos, so it doesn't lead to the female supremacy some might be expecting/fantasising about.