Creating a Article template currently will result in a large wall of text, that can be hard to navigate. And everything not currently in use has to be either deleted or made inviseble on the article page.
An alternative way could be the edditing of the Html structure, reusing exsisting template fields. This will lead to the entry fields, both in name and functionality, being unconected to the use in the article.
Currently the only way to even come close to my sugestion is entering a json object.
My sugesstion is the creation of an advanced Article Template creation tool, where users can create article templates, together with an iterface that has entries just like the standard ones.
I imagine it to work like this: You create an advanced template, selecting one of the standard templates as a guide. Now you have the option to edit the existing entry fields, modefying the title or description. The more powerful option would however be the ability to add or remove more entry fields and catagories.
It might be a good idea to make the article templates sharable, like the generators. Here it might be possible to copy the template into your own collection.
This feature might also reduce the number of requests, to update the standard templates.
With what Sh4d0wPh03n1x said, it is possible for Grandmasters to do this already, which can be found down in the "Creative Studio" under "Article Templates." However, Lucifer_oO is also correct as you can also do this in a generic article.
Everything you proposed is already doable. You can create generic article, and organize it accordingly to your needs.