"please let us know if this service interruption (some services possibly up to two weeks) could be a major impact to your product release schedules".
Well, given that:
The IT services provided by those facilities included virtual systems, control desk, software configuration management, build automation, ID build automation, appscan source vulnerability scanning, and continuous delivery with UrbanCode Deploy
I would suggest it might have an impact?
I wonder if this is a somewhat drastic method of finding out what services they need to keep... turn 'em off for two weeks, and if no-one complains, they obviously weren't required.