The original plan was to simply get rid of deprecated stuff, change a few names here and there and have few compatibility breaking changes.
However, now shade may adopt the SDK and move some of its contents into it. Then shade would consume the SDK, and OSC would consume it as well. It would be pretty clean and easy to use, but would mean major breaking changes for OSC4. OSC would become a shim layer over osc-lib. The plugin interface is going to change, as the loading time is long - every command requires loading all of the plugins which takes over half of the loading time even though the commands themselves load quickly. (There will be more communication once we understand what the new plugin interface will look like.) OSC4 would rip out global argument processing and adopt os-client-config(breaking change). It would adopt the SDK and stop using the client libraries.
Note that this may all change depending on how the SDK situation evolves.
From the end-user perspective, some option names will change. There is some old cruft left around for compatibility reasons that will disappear (e.g. "ip floating" will be gone, it changed a year ago to "floating ip"). The column output will handle structured data better and some of this is already commited to the osc4 feature branch.
The order of commands will not be changed.
For authentication, the bevahiour may change a bit between the CLI behaviour or clouds.yaml. os-client-config came along and changed a few things, notably with regard to precedence. The OSC way of doing will be removed and replaced with OCC.
Best effort will be made not to break scripts. The "configuration show" command shows your current configuration but not where it comes from - it's a bit hard to do because of all the merging of parameters going on.
The conversation continued about auth, how shade uses adapters and may change the SDK to use them as well: would sessions or adapters make the most sense? I had to attend another session and missed the discussion and conclusions.
There was a long discussion around command aliases, as some commands are very long to type (e.g. healthmonitor). It was very clear it's not something OSC wants to get into the business of managing itself (master list of collisions, etc) so it would be up to individual plugins. There could be individual .osc config file that would do the short to long name mapping, similar to a shell alias. It shouldn't be part of the official plugin (otherwise, "why don't we just use those names to begin with?") but it could be another pluging that sets up alias mappings to the short name or a second set of entry points, or include a "list of shortcuts we found handy" in the documentation. Perhaps there should be a community-wide discussion about this.
Collisions are to be managed by users, not by OSC. Having one master list to manage the initial set of keywords is already an unfortunate compromise.
Filtering and others
It's not possible to do filtering on lists or any kind of complex filtering at the moment. The recommendation, or what people currently do, is to output to --json and pipe the output to jq to do what they need. The documentation should be extended to show how to do this.
At the moment filtering varies wildly between APIs and none of them are very expressive, so there isn't a lot OSC can do.