The Economist has a long piece about the impact that ubiquitous genetic testing will have on health insurance, especially in the United States. This part is crucial:
…If that is the consequence, then other ways of paying will have to be devised. Carol McCall of Humana, a big American health-care provider, thinks a move toward some sort of compulsory, universal coverage is inevitable, even in America. That need not necessarily mean a scheme financed mainly out of taxation, of the sort found in most other rich countries. However, social outrage over a rising class of uninsurables may make the government an insurer of last resort-particularly, as Dr Cecchetti observes, when some rich and powerful people discover that they, too, are not immune from the genetic lottery. He reckons testing will lead to individuals receiving a health score akin to today’s personal credit score. Those whose files come on screen to the accompaniment of flashing red lights will not find it easy to obtain cover for much less than the cost of paying for their treatment themselves.
Actually I think the key here is family. Just as surveys have found that having a friend or family member who is gay tends to change how one perceives attitudes toward gay rights, my own hunch is that genetic predispositions found among the circle of family and friends will tend have more of an impact than we might think. The distribution of mutational load being what it is it seems likely that uninsurables will be found across all classes and socioeconomic clusters, as opposed to the current population of uninsured which is disproportionately young, poor or marginalized in some way.