The UK partial privatization is only one model.
Here NAV CANADA was formed as a private, non-share capital corporation -- there are no shareholders! People who opposed its formation on the basis of "shareholder value" compromising safety had no clue what they were talking about.
As a whole, controllers were probably one of the largest beneficiaries of the privatization. That's because prior to privatization, budget was a political football and as a result controller salaries were effectively frozen for years.
And if you look at FAA struggling with modernization issues, NextGen, etc., due to the government bureaucracy -- the experience with NAV CANADA has been completely the opposite. As a private company, rapid adoption of new technologies have been possible.
E.g., the collaboration between NAV CANADA and Iridium for space-based ADS-B technology would have been completely unthinkable had the ANS remained under government bureaucracy.
Of course there were bumps in the road, but looking back, ATC privatization has been very successful here, and I expect for many other countries in the future.