I'll see all of the Star Wars movies. I'm sure they'll all be profitable... For a while, at least. But my point is that there is high potential to fuck things up. I say this fully realizing that the prequels exist and didn't kill anything.
Marvel is kind of a different animal. I am much less of a Marvel guy, aside from knowing the stock very well before it was bought by Disney. I'd have said back then that I had a lot more faith in Marvel than in Disney in terms of keeping things going, but Disney has clearly done a good job (w/ the movies, at least). I do think, however, that the Marvel universe is different than Star Wars in that the jury is still out as to whether or not anyone gives a shit about a non-Skywalker movie (even Rogue One was tangentially a part of it). What is to keep future Star Wars from just being some generic space action movie?