I was just over at the PHPMyAdmin site and saw this quote:
Welcome to phpMyAdmin 2.11, which will probably be the last series supporting PHP 4.
Notice the “probably” stuck in there. They are testing the waters.
If phpMyAdmin is dropping the whole PHP 4 line, it just might push the WordPress adoption time a bit further. Where phpMyAdmin goes, I have to think, the ISPs will not be slow to follow.