While it is true that money could possibly be made indirectly and around the product (e.g. training, support, ads), the questions surrounding doing the equivalent of turning their IP into open-source remains. Usually, dominant companies don't like change or having to figure out new ways to obtain revenue, other than what's direct and obvious to them.
As for customization and plugins, that looks to be an AI versus IP problem too: (1) that companies would turn to Adobe or Microsoft, versus using their own AI (2) 3rd parties reverse engineering their plugins with AI.
Most likely way that it appears possible, is some type of licensing deal between the AI company and the original IP owner. Would be surprised if they do that smoothly, prior to lots of court fights, because corporate types usually don't like to share.