Sure, but that probably entails having add-on publishers go through them. Laminar basically becomes the publisher which probably is baggage for them, and having to work with them is baggage for everybody else. Not to say that it couldn't work, but it is different from the we-take-care-of-the-engine/api-anything-else-goes approach they have today. Does Train Simulator let users build/install their own routes/trains/etc, much as FSX and X-Plane both do? I think a big part of what killed MS Flight was the fact that it was a closed environment - if you wanted to add a region or plane you had to buy it from MS at $20 each or whatever. Sure, the gamification was an issue for many, but there is no reason that you couldn't have realistic add-ons (free or commercial), as long as the underlying engine supported navaids, ATC, etc. The idea of either flying a 747 over an ocean world between two islands (brings back memories of the 80s), or buying $5000 worth of add-ons to have VFR scenery of a great circle route is a non-starter for anybody serious. (Apologies - I realize this is drifting in topic.) Back to the point - if Train Simulator doesn't allow users to add their own routes/etc, then that is why there is a huge library of DLC in Steam. That is their whole business model, like selling Guitar Hero songs for $5 each. There is no way that would work for X-Plane, and Laminar obviously knows that. It would be better if 3rd parties had the option of selling through steam and still having it work seamlessly with X-Plane. That could be a real benefit to everybody, but I'm not sure about technical issues (presumably everything goes in its own directory and X-Plane would need a mechanism to load the right stuff at the same time - probably no more big self-contained X-Plane directory).