I can confirm that after a person in a household passes the 100 year embargo rule, the stats for everyone else in the household remain unchanged and still show them as unavailable.
Thus in the example I found with three people, P1, P2 and P3 of which the last was born 1917 but is now viewable, appear as thus:
Looking for P1 shows P1 + P2 +1 unavailable;
Looking for P2 shows P2 + P1 +1 unavailable;
Looking for P3 shows P3 + P1 +1 unavailable!
As an aside they all appear with the surname N which subsequently changes to the correct (though mis-spelt) surname. Has anyone else found this?