Thanks for the questions!
Subs… Well, subs have been, and continue to be, discussed internally in several different contexts as they can relate to Extensions. I am certain that something will occur in this space, and it is more of a matter of when, rather than if. Given that there have conversations around different uses subs, it is difficult to say which path is likely to be taken first (second, or third) just yet.
Variable revenue shares have been discussed internally, for both In-Extension Purchases, and Bits-in-Extensions. I expect that this will evolve as we try to find a sweet spot that balances between requirements of developers and broadcasters. It is very clear that a one-size-fits-all approach will not work for everyone. That being said, we need to start somewhere.
Monetising streamers… This already happens today! A number of developers already do contract Extension development work for streamers. Over time, we will likely provide more (and different) supported avenues for monetising Extensions; a number of different strategies have been identified, but most of these have yet to be explored.
European events. I’m an engineer, so I can honestly say that I have no idea. @Amorelandra can hopefully answer this question far better than me.