It would be really great to have Dynamo integrated in Inventor, in a similar way that now is integrated in Revit
Dynamo is being developed very fast. And from last year they have totally reorganized it to allow to be hosted in different platforms.
Its internal solid engine is similar to the Inventor one. And If you are used to create solid or surface geometry in Inventor you will be familiar very soon with its methods for solid and surface geometry. Indeed, the Inventor part environment seems a rather convenient platform for Dynamo as pure geometrical exploration tool.
There are already some personal efforts to integrate Dynamo in Inventor:
https://github.com/frankfralick/DynamoInventor
Because you can use Dynamo as a standalone app and import/export sat files, you can currently manage somehow to use Dynamo complementary to Inventor. You can read here (at the end) about a specific sample of this workflow:
http://dynamobim.com/intersecting-rails/
But obviously this way of working is never going to be as convenient as having Dynamo hosted in Inventor.