Having developed their OS before FOSS was a threat, they can make their money tending to existing clients who find it challenging to exit or substitute Microsoft software (interoperability). Meanwhile, they give away their software as inexpensively as possible in new markets, and, in particular, targeted for maximum effect to nip Linux growth in the bud. It also helps they have a load of cash, connections, brand (they are the devil people know), and an ethically challenged management.

I think the government and private sector can *demand* source code be made openly available (for privacy, security, and extra flexibility/value). Alternatively, the government might want to insist on standards and exact heavy penalties whenever it is found Microsoft has broken a standard or extended it in secret ways (obviously, Microsoft breaks and extends standards as a matter of course.. that is how they build up lock-in secrets).

Without one of these two demands on Microsoft (and on closed source vendors in general, but in particular on Microsoft as the vendor of the main platform and key applications running on it), FOSS will have a more difficult time getting traction (it will grow, but there will be costs to be born by those trying to grow that market).

I think the government can justify either of these free market moves on behalf of the public interest, even without having to go into antitrust actions (though it may very well be that Microsoft has broken laws, eg, dumping, illegal contract terms, etc).

As for those trying to grow Linux market share, it obvious can be done. Perhaps the main reason for difficulties could be found in the contract terms with hardware OEMs and other Microsoft partners, but surely buyers should be more demanding (as I suggested above). This is especially true of the government as a representative of the people and with a need for transparency and the avoidance of creating monopolies by instilling lock-in at a wide scale through their support of closed source products.