Is moving to Lightroom CC a one way street regarding image edits?

I'm not clear about what you want to do with the locally stored copy of the originals. That option is basically to allow the user to be able to work when the local system is offline (e.g. travelling with a laptop into remote areas), and just like Classic they are original files only and all the associated edits are retained in the local and cloud catalogs. The only difference between Classic and LrDesktop is that Classic does have the option to save metadata to XMP, thus storing the edits in the file header or XMP sidecar (depending on image format), but even then that edit data is generally only useable by another Adobe app. What is it you wanted to use that local copy for?

In terms of migrating back to Classic, there are a couple of methods, both with some drawbacks. Assuming all the images in the cloud are originals, not smart previews synced from Classic, you could either:

1. Simplest method is to create a new empty catalog in Classic, then open the Classic Preferences>Lightroom Sync tab and there set the download location where you want the downloaded images to be stored. Also set the folder structure from one of the standard Lightroom date-based options. Once that's done, enable cloud syncing.....that will then download ALL the images in the cloud to the local hard drive as per the set location, storing them in the capture date-based structure that you selected. It's as simple as that, and once downloaded (and checked and then images and catalog backed up) you can delete the contents of the cloud (optionally resyncing smart previews from the new Classic catalog back to the cloud). Whilst all edits are retained, and most other metadata (albums in Lightroom will appear as collections in Classic, but the Folders do not sync so you'd need to manually recreate the Collections Sets in Classic), the main drawback with this method is that any Keywords, Location Data, People data that you may have added in Lightroom is NOT downloaded and so would be lost and the work would have to be redone in Classic.

2. If the missing Keywords, Location Data is a show-stopper, the other way of migrating back would by by exporting all the images from the cloud using the "Original" option, then importing the exported files into a new Classic catalog. That would at least retain all the missing data from the sync download method, but it also has the drawback that the XMP data in the exported originals does not include Collection/Album membership....so you would lose all that work. The workaround for that would be to add album-specific keywords in Lightroom before doing the export, which would allow you to at least rebuild the collections in Classic from the keywords that you added. You'd also need to think about physical folder storage options....if you exported all in one go from Lightroom they's all end up in a single folder. That's OK, as when you subsequently do the Classic import you could use the "Move" option and choose one of the date-based folder schemes in the Destination panel.