Just one use case:

Being on the way with a mobile phone, gathering information, by bookmarking links and saving web pages for offline reading. Later it becomes of interest to go through all that, but now you have a tablet at hand. Bigger sized and more convenient for relaxed reading. You wanna quickly get all the freshly (and only these) bookmarked links onto the tablet, to quickly look them through and save the one or other site for offline use as well. Then you enter the plane, and being online becomes the past, for some hours. Now you have time to move also all the latest offline pages from your mobile phone to the tablet, for relaxed rading, and you have time for that as well...

It should become possible to synchronize settings, bookmarks, offline pages between devices being directly coupled by WLAN, NFC, Blue Tooth, whatever - getting rid of the way through the Internet.

As a less comfortable solution would be nice, to have full access on all those data. For instance by optionally saving it in user-defined folders. Then easily helpers might be written to support synchronization in a convenient way, inclusively good options to filter in both directions which data actually shall be synchronized (by type, time, ...) and in which direction (both or only one).

Finally it should become possible to decide where the offline pages shall be stored and thus become possible to interchange them between devices.

It's so easy to connect two devices via WLAN. For example. It's so often that by mobile phone I gather some articles for later reading and then, when I had time for reading them, I also have the tablet available. Then I want to copy them to the tablet. Ideally it might be some 'synchronize' function, but if, than an intelligent one, which means: controlability what parts are synchronized, what differences are remaining. Probably just providing file access will be easier to implement. And no, using the internet for this copy process is no option. Anyway synchronizing devices should not be done via Internet 'clouds' - direct connections are a better idea. Cheaper, faster, more secure.