I would agree there with News at Ten. Very impressive but probably the most short lived.
Certain regional news programmes have been in a Similar position where impressive new looks are abandoned soon after due to a corporate rebrand
Yeah, as well as the North West Tonight example that was posted, there was also three ITV News regions whose packages lasted less than a year - Calendar, Anglia News, and Granada Reports. Clearly Granada somehow didn't know about it until it was too late, and it wasn't the first time they'd been caught short like that...
There's also the 1999 YTV idents, relegated to local use, and the 2000 Tyne Tees logo, which must've already been in production at the time and also got relegated to local use (they didn't even update the generic hearts idents, even when the ITV1 change came in). Granada was also supposed to get a new logo but theirs was abandoned.
1988 Tyne Tees, flowing rivers, is another example. Lasted just under a year, replaced by the 1989 generic look.
And I think Thames's 1991 ident was probably made for launch in 1992. They launched it almost immediately when they found out they'd lost their franchise. It definitely would've lasted a few more years (at least as long as that logo was on the endcap) if they hadn't lost out to Carlton.