Nah, Microsoft makes good money from Visio licenses - I'm sure it more than pays for itself and helps keep the megacorps locked in. All of our org's corporate laptops come with Office but you can request Visio if you need it - the license cost gets charged back to your department.
The mentioned alternatives also don't compare to what Visio has in terms of breadth for iconography, etc. It's just a bit better, which may not always be the case. That said, MS is definitely making enough to keep that ball rolling in terms of development.