I do love ITN as a brand and agree with the OP it has a lot of prestige even still.
I wouldn't be against them using the ITN name on ITV/sign offs. However it looks more like they will be possibly reintroducing the programme titles like News at Ten, Evening News and so on. It's almost like they brought back "ITV" for the main channel ditching ITV1 which was always a bit cheap.
Even though the idea of ITN brand coming back is nice, I agree with Square Eyes it would likely make no difference.
They did of course keep the ITN name around for a short while after the 1999 rebrand. 'Journalist Name Reporting' astons had an ITN logo and they signed off "for ITN" IIRC.