If it's perfectly predictable, but takes effort, then insurance companies would be replaced by (or pivot to) companies that sell the service of telling you your

If it's perfectly predictable, but takes effort, then insurance companies would be replaced by (or pivot to) companies that sell the service of telling you your predictions. (If the prediction takes no effort—open source software, very little computation—then this cost will approach zero, and the more tech-savvy would do it themselves. Maybe OS vendors would bundle it as a convenience.) Then each person knows in advance what medical costs they'll have to pay—or choose to not bother with—and can plan accordingly. Realistically, I think that having perfect information about one person and about biology and stuff still doesn't give you enough information to predict whether they'll get various diseases. If there is any validity at all to "exposure to X causes cancer", then no amount of information about one person will help you predict whether they'll get exposed to X. Or whether they'll trip, fall, and break a bone. And, really, I expect that the perfect state of knowledge of human biology would merely allow you to deduce "person X has x% chance of developing disease D during the next ten years; person Y has y% chance". So there would still be a role for insurance companies for the risk-averse.