Is there a way to render a node with view mode via token?
So the question is how to insert something like [node:5:teaser] into a formatted text area and get the teaser view of node 5.

This can be done with a combination of modules:

Token Filter (D7,D8)


  Token Filter is a very simple module to make token values available as an input filter.


So (after adding that filter to the text format), for the current node, we can use e.g. [node:title] in formatted text.

Token Entity Render (D7, D8 Issue)


  Provides tokens ([entity_type:render:view_mode_name]) that render full entities using view mode specified.


Advanced Entity Tokens (D7, D8 Issue)


  Through AET you can query the DB for entities using Tokens.
  Examples: [aet:node:1]


Putting it together

In the end you should be able to use [aet:node:5:render:teaser] in your formatted text.