The TouchDown icon was gone from my devices "desktop". Went through the different "desktop"-pages and the "Apps" library several times. Nothing. Looking in "Contacts" I could only see a smaaalllll, strange icon, an envelope, which I didn't recognize and hence it was an icon for "we have no idea what this comes from".
When you now asked me to look for the TouchDown-account I assumed that would be gone as well. But no, there it was. But with the same, new "insignificant" icon as in "Contacts. Went through the "desktop"-pages again. Nothing. Went through the "Apps"-library again. Several times. And then, suddenly I found not only the old, familiar TouchDown Pro License icon but TouchDown with this new icon. I opened it and everything worked. Only had to put it back where the old icon was on the "desktop".
Case closed.
Maybe blind but this was a bit unsuspected and bad (lacking) information from Symantec's side.