Arranging a DNR ahead of time is literally the only option, lol. Not having one means that the medical team will immediately start cardio-pulmonary resuscitation. A decent team would hopefully make an early decision to stop the resuscitation if the patient was clearly frail and unlikely to make it out of hospital. It’s one thing to get a pulse back and the patient be “alive” - it’s another entirely to move into post resuscitation care in ICU, and then survive the next hours/days/weeks/months.
As explained above in one of my earlier comments, current circs are largely irrelevant, of those very few people who do survive a sudden cardiac arrest, fewer still return to normal life exactly as they left it. Even young people who survive a cardiac arrest can have poor neurological outcomes meaning they need carers, mobility aids, cognitive help, some even need 24/7 care in a nursing home (I used to work in a young persons neuro/spinal injuries unit, there were some really unfortunate situations where people had survived the cardiac arrest, but left unable to do anything for themselves, bed bound and furious at life, due to hypoxic brain injuries caused by the cardiac arrest, etc). For an elderly person with existing physical frailty, chronic conditions, maybe some degree of existing organ failure, etc - chances of returning to their lovely life of pottering and independence are incredibly slim.
I think films and TV have given the public an unrealistic view of cardiac arrest/CPR - I think people might expect that they have a few half hearted chest compressions, immediately get a pulse back, the person is spontaneously alert immediately and going home the next day. Most of the time when you do get a pulse back, the person remains unconscious for several days, if they ever regain consciousness, is intubated and on a ventilator and the prognosis is generally grave.
I’m not saying we shouldn’t ever resuscitate anyone, but I think we should be a lot more selective and realistic. But it isn’t a failing of any individual family to not their relative to have a DNAR, it’s a failing of the system, media, medics, etc to not have explained in a understandable way the use/implications of them.