Nicely put, ThunderPeel. Of course the next movie might hit all the right notes and be a big succes. Could be, and if it does, good for us, and for Disney/Lucasfilm.
I guess I just like the Back to the Future approach to moviemaking more. Robert Zemeckis said there will be no sequels/prequels/midquels/reboots or anything as long as he lives, and I think it makes the trilogy extra special. I just don't like what these franchises become when they're trying to stay relevant. Indiana Jones was perfect as a trilogy, I can accept that there is a mediocre fourth part starring an aging Indiana. But after this, 2/5 of the franchise will be about an aging or even elderly Indiana Jones...
I'd like it best if they just let bygones be bygones, and focus on something new. Remember Indiana Jones as a great set of movies, instead of constantly trying to live up to old glory with an elderly actor... and mixed results.
And if a fifth movie is unavoidable (which by now it probably is), I'd like it to be made with Ford, Spielberg and Lucas, because that's the trio that made the magic happen. Without them, there would be no Indy, so to me, they are the only people who should close the book on him, (even if it delivers a mediocre fifth film).