iCloud Catch 22 - Cannot sign out of old dead Apple ID on iPads
Prior to the upgrade to iOS 9.02 this was unresolvable without going to an Apple Store with proof of purchase.  With 9.02 it you can work around it.
The steps I used were: 


At the Apple ID site, change the Apple ID email to "oldemail@oldcompany.com" -- this will never be verified.
On the iPad go to Settings|iCloud - It will ask for the password.
I logged on with the correct password - it now greys out the entire iCloud area and puts a Validate Email message at the top of the form, BUT does not grey out the Sign out.
I Signed out and it asked for the password twice again, paused for a long time and then was asking for a new iCloud Apple ID.
Back at the Apple ID site, change the Apple ID back to the valid account.
From the mail client, validate the Account with the correct password.
On the iPad, Settings|iCloud enter the new Apple ID and password.


Poof - problem solved