The issue of whether or not these insurance companies can pay the claims is seperate from the issue of a government guarantee.
Will the government need to step in and bailout these 3 insurance companies that guarantee fnma mortgages? Maybe. That is another question for another day, even tho most of that will fix itself...the PMI rates keep going up because of a high number of claims. FNMA shareholders are frankly largely unconcerned about the health of insurance companies. This is a seperate issue. If you think the insurance companies are unhealthy, then perhaps you should not buy MBS as an investment.