Now that Dropbox has implemented a three-device limit, there will probably be quite a few folks out there who can no longer use it with Editorial. Any chance of adding support for other popular cloud services, such as Box or Google Drive?
Exactly. I have used Dropbox for a long time, but I have a desktop, a laptop, an iPad, and a phone. And other cloud storage systems give me more disk space or integrate better with my work. Now that Apple has implemented an API for working with any sort of storage, include WebDav, there's no excuse for being "Dropbox only." And now that Dropbox is unusable, so is Editorial.
+1 for me. Three-device limit was the final push I needed to abandon dropbox. Seems likely that other "free" cloud storage providers will also sharpen their free provision to push users towards subscriptions, so I'm self-hosting with NextCloud and haven't looked back. WebDAV would be a practical approach in this case, as webdav is supported natively in nextcloud. In any case, it seems the days of dropbox being the cloud of choice for power users is limited.
Here's a solution for you, if you're still looking for one
This isn't a cloud-based service at all, but this is an existing solution that already works great for me, even when I'm no where near a working internet connection:
Editorial is a "File Sharing" enabled app, which means you can connect your iPad / iPhone to your Mac through a USB cable, grab whatever files you want, and either transfer them from some folder on your mac into the Editorial app, or go the other way. Another app you could use to do the same things is called iMazing, and there may be others as well. iTunes is free, and you may have it already. iMazing also allows the connection to happen through a shared local WiFi.
Besides being able to do this without an Internet connection, another thing I like about this method is that it always works for me: I've never lost a file yet with this kind of transfer, and I've been doing this kind of thing for many years with other apps. That matters more because I've read other people's reviews saying they lost data through the Dropbox synching. Maybe it would also avoid any time wasted, waiting for dropbox to notice that a synch needs to happen and doing it, but I don't know about that as I've never tried synching through Dropbox yet.