I don't really see what it will achieve by moving the regional news 'inside' the national news and cutting it back. To me, its just rearranging the deckchairs on the Titanic. It won't steal any viewers from BBC News
It's been apparent for many years that ITV plc would dearly love it if they could drop regional news altogether at some point in the future. Blurring the distinction between the regional and national news as much as possible (thus making the regional news much less "appointment-to-view" friendly in its own right) is a good way of easing the journey towards such an ultimate goal.
After all, if the regional insert were, say, at 6:10pm-6:30pm or something, and listings/EPGs etc listed the 6pm-7pm slot as a single programme, then for any given viewer to specifically desire to watch the ITV regional news without also watching some/all the ITV national news, becomes less possible. Also, it could be that *in practice* the regional insert rarely airs on time, but rather moves around a bit daily (e.g. on a given day, it might actually air from, say, 18:08:45 until 18:28:45 or something).
If the very existence of the regional programmes become increasingly "invisible" to casual viewers, then that paves the way for them to be dropped with most people barely even noticing that the axe has fallen, thus avoiding many complaints about it. I can well believe that this is the path that we may now be on.