Pamplinas & Aldegar,
Maybe I'm wrong here (and please correct me if I am), but is it not true that all Aena ATCOs (native Spanish or otherwise) in the towers to be privatised, were given a deadline (possibly January 10th?) to decide whether they wanted to remain employed by Aena and be stationed elsewhere, or to remain in their current stations/towers and be employed by FerroNATS or Saerco?? In other words, they would not be forced to leave their current stations, but could choose to stay where they are and adopt the new working conditions of their new employer. Therefore they do have a choice and are not being ousted by mercenaries.
If this is the case, it is quite possible that some Aena ATCOs would leave while others might decide to stay. Then Daermon, the FerroNATS/Saerco staff could well be working alongside those Aena ATCOs (and any of the 150 cadets who are subsequently trained in) for some time to come, after their own initial OJT is complete, and not as you say "never see another Aena ATCO again."
I myself enquired about the FerroNATS position. I was told the number of vacancies would depend on the number of Spanish ATCOs who decide to leave their respective towers and stay with Aena. The FerroNATS job would involve being/becoming an OJTI (and eventually supervisor or 'Tower Chief') and moving from tower to tower, training in as many as required of the 150 cadets, until all vacancies are filled in all of the privatised towers. Level 4 Spanish language is required, especially in quieter airports where its used on the frequency as well as co-ordinating with other units/airport personnel. There will be an exam(s) in Senasa college in Madrid. Post-privatisation, FerroNATS staff would have the option of remaining in Spain for the entire 5+1 year contract and longer, and of being employed by the next contractor should FerroNATS lose the contract next time around.
This is what I heard, please feel free to say otherwise if you heard differently...
I also agree with Aldegar, that this is just another job vacancy and people can apply for it from whatever country/background they wish, without being labelled a mercenary. They are simply agreeing to the conditions that other Aena ATCOs are voluntarily rejecting. Yes there will understandably be friction between FerroNATS/Saerco staff and other Aena ATCOs initially, but all Spanish bitterness and resentment should instead be directed at Aena for their gross mismanagement and refusal to recruit more staff years ago, which would have avoided the massive overtime bill that crippled the company with debt, and the December 2010 strikes that provoked the new laws.