I know this comment will be going a little soap operish BUT, imagine if Daenerys is pregnant with Jons child. The unborn child would be the future Targaryen King/Queen, undisputed......fade to black and a future series.
To me, what Danaerys really did last night was not win the throne, but rather just destroyed it both literally and figuratively. There isn't an Iron Throne, and there really isn't even a King's Landing any more.
Might not be a bad way to end the series.
It’ll make billions if they continue the storyline.
You know folks will watch it, and once you have an established story with characters and plots that can be laid out in a million different ways it can literally go on forever with good writing. Think Star Wars before the last batch of bad movies.