This
Forbes article is a helpful explanation of the complicated choices facing insurance companies as their customers embark on a completely different scheme of self-selection from the one that has driven actuarial planning up to now. It seems that the ACA tried to guard against some kinds of self-selection and their resulting death-spiral dangers by requiring insurance companies to create one risk pool for all of their customers, regardless of whether they purchased their insurance on or off the exchange. The law's architects did not take fully into account, however, how many insurers might decide to boycott the exchange altogether. Boycotting insurers are free to price their products on the basis of their own pools. If I understand the author's argument, this is likely for several reasons to result in a divergence of the risk profiles that will favor the competitive position of the non-exchange insurers even on their ACA-compliant products.
Pricing is only one aspect that may vary sharply between exchange and non-exchange products: there is already considerable pressure on exchange products to shrink their provider networks and covered drug lists. I've become interested in Assurant Health, an insurer that decided to boycott the exchanges. Its prices for a Bronze plan are slightly higher than those of Blue Cross, but its network is the old-fashioned universal sort. The article cites to a detailed brief on risk pools, including this explanation of why network shrinkage may be a more powerful cost-control issue than I realized:
Prohibiting [denial of coverage for pre-existing conditions] leaves insurers vulnerable to attracting a disproportionate share of patients with poor health risks. This vulnerability might cause them to leave the market or encourage them to use more covert or indirect means of risk avoidance, such as selective marketing or structuring their provider networks to exclude the doctors or hospitals preferred by higher risk patients.
It's not just that excellent hospitals like the Mayo Clinic or cancer centers charge high rates. It's that they attract exactly the sort of patient that an insurer needs to avoid if it can't tie its prices to the health status of brand-new customers.