Anyway the Hashemites are much better than say, the Sauds. Not saying much though.
The Hashemites might have gone the way of the Sauds, were it not for the Sauds.
Losing the Hejaz basically forced them to cozy up to the British and remake themselves into a more cosmopolitan, Western-friendly monarchy that the British found acceptable and were willing to give Transjordan and Iraq to.
So now you've got a half-Jordanian, half-British monarch with an American stepmother and a Palestinian wife. His son and heir apparent is a college student living in the US, so it's not too farfetched to think he might marry an American woman. After a generation or two, you'll have a Jordanian king that's maybe only an eighth or a sixteenth Jordanian. It's not too far removed from the old days of grab-bag monarchies in Europe, like when Greece was a kingdom with a German-Danish royal family.