As others mentioned already, we will have the server side rendered UI still for quite a while.
There will be alternative UI’s from the ClientSide world, but before this will replace everthing else, there will be a lot more watter going down the rivers.
Mosaic is a good and useful thing. We should put some effort in it to make it a bit more stable and add some more nice templates, especially for the listing tile (collections). At least for the content area I like to have Mosaic in all my projects. There is some room for improvements as in the management of the custom layouts, but that does not mean it isn’t useful as it is. And the core elements the tiles are already in the core and are quite useful.
We should define a way, how one could use it as a default for all pages or for just some custom content types, which is what I usually do. The custom content type way is nice, because you can wire it with a Mosaic content layout template together and enable it by default.
Maybe plone.app.mosaic could add another content type which is a basic Item (Page) like content type with just the default behaviors enabled and Mosaic enabled be default. This way users could just add these Mosaic page and use Mosaic easier. You could still add normal pages, there is nothing wrong in this, if you don’t need a more complex content layout.
This in place I don’t see why we shouldn’t ship Mosaic with Plone core. It will not replace anything and doesn’t have to be enabled by default as the working copy support is not. But it’s way easier to use then and also good for the marketing team.
Let’s improve Mosaic now and use it. Even if not for any use case, but for content layout it’s preatty useful.
@datakurre you made some improvements for your university. Do you have a plan when you can move this into the package?