The ability to update imagery layers while maintaining the same external URL/itemid is essential for encouraging the wider use of image services. Hosted image layers need to support an 'overwrite' option so that they can operate like other types of service.
This is a deliberate generalisation of an existing idea, which was focusses on multidimensional data.
Overwrite multidimensional hosted imagery on ArcGI... - Esri Community
I'm also going to raise a complementary idea to support something like an Image Layer View as an Image version of how Feature Layer Views work, mostly to support hot swapping live image layers.
