Hey @ernie 
Thanks for your thoughts 
Shortcodes won’t be a thing in Ghost but the new Koenig is designed to eventually be extensible via custom cards that could also register their own text expansions. I think that would cover all typical uses of shortcodes.
Apps are definitely on the cards, you can add your vote and ideas to the Ghost Apps topic on the ideas board.
You also mention a number of things such as e-mail newsletters and so on that won’t necessarily be apps but are definitely planned as part of our Memberships & Subscriptions feature that we’re currently hiring for.
Definitely! The plan is to allow for custom cards and text expansions to be registered/installed. We’re also only just getting started with what’s possible via the cards interface, expect a lot of exciting things in this area 
Cards really can be anything, you could have a podcast player card, or a slideshow, or an image gallery card to name a few simpler ideas.
The underlying structure of Koenig also opens up a lot of additional possibilities we’d like to explore such as being able to create content templates. For example, adding a “recipe” template that defines the structure of a typical page on your site. The template could consist of a number of cards (image, ingredient list, cooking steps) as well as rich-text areas (description) that would be pre-populated as blank areas for you when creating a “recipe” post.
Another thing to keep an eye on is the Dynamic routing work that will allow for a lot more control over your site structure. It should also eventually allow things such as your suggested “email view”, alternate feeds, and a lot more.
I think in short, the answer is: “Don’t worry, we’re thinking about (and working on) all of these things!” 