re: it’s awesome x 2.
re: what happens to all our directory pages that rely on the existing shortcodes?
First, the shortcodes themselves are not going away (Yet. I’m hoping in a future update that I will also be able to “replace” the shortcodes using the Customizer too. We’ll see, that will be far more complex to accomplish). It is all the shortcode options for the templates that are going away.
The template shortcode options will still exist and more importantly still work. I guess more accurately the template shortcode options are going to be greatly de-emphasized in favor of the Template Customizer. Under the hood, the way it’ll work, is the Template Customizer will set the template shortcode option defaults. If you choose, you can then use the template shortcode options to override those defaults per shortcode instance.
What this means to a novice is they get an interactive point and click interface which will make it extremely easy to tweak the million and one template options. For the advanced user, they can set their own template defaults using the Template Customizer and when they use they shortcode, they will still have the option to use the template shortcode options to override the settings set by the Template Customizer. For example, you can set up Slim to be close to what you need globally and on individual pages where you might need specific tweaks you can use the shortcode options to make those tweaks.
I hope I’ve explained that clearly! It’s very much like a parfait… it has layers :D