Yeah, only way that could happen is if it replaced the 6pm AND 10pm bulletins. Ofcom would never allow that.
Why not? People seem to forget that the Evening News & News At Ten have only co-existed for a relatively short period of time. Prior to 1999 there was a short bulletin at 5:40/5:45 and the main news at 10pm. The ITV Evening News was basically News at Ten brought forward, and the Early Evening News was shoved to 11pm as the Nightly News. It's only when News at Ten returned that there were two major news programmes on the channel.
I'd say having a main news programme at a peak time which doesn't clash with the other side would be welcomed.
There would still have to be an early evening bulletin on ITV.
ITV isn't going to move The Chase, which occupies the 5 p.m. slot. Furthermore, there would be a further decrease in ratings for national news on ITV if the Evening News was moved.
Besides, having the main ITV national news at 8 would clash with EastEnders.