Wordpress is “open source” and look how many billions that generates. The way Discourse is run can carry on as normal, this will be seperate entity and a case of 'buy the fancy themes or plugins or don’t. Imagine a load of new devs ideas, plugins etc. it would encourage growth of the Discourse platform.
Basically a way of supporting devs like @awesomerobot who has created possibly the best theme on Discourse.