Great point Brian, and I agree, Shotcut is licensed under the GPL, hence any templates or items in the marketplace would be licensed under the GPL as well. also, a plugin framework would be nice, but there is really no need to go that far just yet.
I am more focused on the types of items end-users and folks with beginner to intermediate level knowledge of Shotcut can create, such as video Title templates, intro templates, opener Templates, premade video ad templates, etc.
As those typically form the majority of content available in a marketplace for a video software. Typically any asset that you could just pop into the editor, customize it and render.
For Instance, Adobe After effects is pretty pricey and has a very steep learning curve for the average person, yet it has grown to be one of the most widely used editors on the planet with tens of millions of users, simply because it has a ton of marketplaces that allow any novice user to buy a readymade template project, make a few tweaks and render a great looking video in minutes.
Here is an After effects example marketplace
https://videohive.net/category/after-effects-project-files/titles
This is the same ease and speed I intend to adopt for Shotcut. New users will be happy to jump on board the Shotcut train if they see premade templates that will make their lives easier.