As for needing to provide parts into the future, a friend's company does aftermarket service for many expensive pieces of government equipment. Presumably they're able to make what's needed because the government requires it of the original manufacturer.

The government could require that manufacturers either supply replacement parts or specs for someone else to manufacture them. I suppose the latter would be required to avoid gouging. It'd be interesting to think about the secondary effects—if you can't make a lot of money off of service, will you make longer-lasting products and charge appropriately?