Re: What to do
Another reason to migrate to Linux.
As opposed to all the reasons not to...
I know little or nothing about Linux but in an earlier posting (that you have since deleted) you mentioned training. Quite apart from training costs (to which you made reference) there would be the montrous logistical problem of getting everyone trained to a suitable standard so that they could (hopefully) make a seamless transition to a new operating system.
On top of which the IT support staff would have to be retrained to a much higher level than the users, which would involve a reduction of the support available on the existing Windows systems.
On top of which the IT support staff might well be employed by a Managed Service Provider contracted to provide Windows support, and who then either charge an eye - watering amount to retrain or even make a legal claim that their contract was effectively being cancelled beneath them.
On top of which not all computer functions fall neatly into the "office" (small o) variety; there are all sorts of software (some of them major) that are very much part and parcel of the users' needs, and unless the software will run on Linux (and I would put money on that not being the case) then that function would have to somehow stop, or the software suppliers (who very often supply the software in support of specialist hardware) would have to be cajoled into providing a new version at potentially enormous cost.
The above list does not pretend to be exhaustive.
I am not writing in support of Windows or Microsoft - merely pointing out that for good or ill Windows has become a de facto standard for so many computer applications that simply assuming that a migration to another OS (Linux) is practicable may be seriously mistaken.