True that it's unsurprising that the backroom staff will stay on - but the much more dispensable senior editors are the ones who shape the overall programme and its editorial direction.
This is how it seems to work...
1) Introduce new format, with big name presenter(s) as the main draw. Limit Kate Garraway to a marginal role. Assume all existing viewers will like it. Do very little marketing, relying mainly on cross-promotion elsewhere on ITV.
2) Panic when launch ratings are disappointing. Reintroduce some TV-am/GMTV-style features, ignoring the fact that these featured most heavily at the previous programme's nadir.
3) Go into meltdown as ratings slide further. Revert to format and content almost indistinguishable from TV-am, GMTV and the previous programme before it got axed. Significantly increase Kate Garraway's screen time.
4) Axe programme due to record low ratings.
5) Repeat steps 1-5 ad infinitum.