I suspect the reaction from a lot of companies is going to be to lock down internal documents under a need-to-know security model.
That's why I'm glad he released as much as he did, any followup whistle-blower leak is bound to be much much harder.
Second reaction: Huh, employees were locked out of their offices, VPN was surely down, yeah if there was someone inside the data centre deleting files off their Intranet no one from outside the data centre would be able to notice, due to the lack of connectivity.
But it would have to be a very good scrubbing and people would notice things missing anyway, "Hey wasn't there used to be a PDF here..?". Hah, https://en.wikipedia.org/wiki/Memory_hole