Surely one would cull images from storage on the Cloud that no longer require instant access from anywhere and simply keep back-ups of those old or secondary images on off-line HDs?
Yes, of course. But if it is as some say that "Classic" in Lightroom Classic means "end-of-life" and will be replaced by the new Lightroom CC, then such an option might not be available (from Adobe) in the future.
Use of smart previews in the cloud and editing using those is one thing of course and it may be very practical to some users. However, this doesn't work for me because I use one catalog per project and I might have different catalogs on different computers. If Adobe in the future allows more selective syncing (where images are not restricted to one catalog but can be any images anywhere) and if the original images can be downloaded with edits to a LR Classic catalogue on another computer then this is something I could use. At present you can upload images from any device using Lightroom CC but it is not clear to me how the originals will be recovered from the cloud, to continue editing using tools that permit printing etc. I do know that Lightroom CC allows an image to be opened in Photoshop CC and that's all good but what if I want a group of images, original NEFs and edit information to be downloaded for local storage and removed from the cloud?
Anyway, I do believe Adobe is trying to provide an improved service for photographers. However, always when there is a new major release, a lot of details are ... cloudy, to say the least.