I'd go half in the past, half new. Old John McClane is refilling some oxygen tanks for his best friend who is dying of lung cancer. A ride around town from the warehouse depot and supplier, to strip mall clinic to medical center highrise. He has to team up with a young nurse who hero protags the shit out of things when a hospital wing is shut down by some y'all qaeda terrorists/cops who take some doctors and staff hostage over a national viral outbreak and some found service cam footage that would set the city on fire. Tone would be sarcastic as a heart attack. Death lurks just around the corner, die hard indeed. An Alex Jones type tiktoks the whole ordeal from the lobby and gets people killed without missing a beat, the big villain is revealed to be a desk cop who kidnaps and tries to disappear his daughter's boyfriend, an EMT, because racist paranoia and peer pressure and everything goes to shit because of common decency and misunderstanding and systems pushed past their limits.