The title does not really enclose all the topics and cover the full value of this talk. Actually it is not explicit enough, because sustainability is a word that is being used in too many contexts and means too much. I would maybe rephrase the title to "The Real Cost and Value of Open Source and Why and How Your Company can Participate and Give Back". A bit clunky, but it tells the story I believe.
@Tobie Langel starts by mentioning ways how open source gets funded nowadays. Though he limits it to the money-funding parts, I believe the employed as full-time open source dev, funding through free license of products, etc. is not included.
Later he adds up the salary of all developers and compares it to the open source funding that open collective has given out in 2018. I am not sure I can fully follow the comparison, since one is salaries and the other is funding for open source projects, maybe I just didn't get why they are comparable. But I think it very well shows the dimensions of value created in the open source space, because if all open source work would be payed I believe the sum of all salaries would be beyond this trillion. But that's just my guesstimate.
He goes on with taking apart the limitation that funding open source just with money has. Pretty nice drill down on the problem. His final conclusion is a bit richer, but let me say this: It is clear that there are not many companies that understand the real value of open source yet.
@tobie The next talk could be about how to establish a sustainable software cycle in companies, that do not just make use of open source.
Watch it, I can highly recommend it.
Another Related Topics
... I just remember is Why I forked my own project and my own company ownCloud to Nextcloud by Frank Karlitschek, Nextcloud Founder. He talks about how and why he re-tried his company and is convinced that doing full and real open source is the better approach.