Arabic Transjordan and Zionist Cisjordan may have been the original two-state solution, but it's not going to work now, even if it ever could have.
Thats always been a naive idea. But a Palestinian state on both sides of Jordan could work if the monarchy were replaced with a democratic republic controlled by the Palestinian majority. It will take a revolution in Jordan of some kind to achieve it, but it would change Palestine from a quasi-state squeezed between hostile Israel and suspicious Jordan to a viable entity with some control over its own destiny. Hard to see it happening, but that goes for all possible solutions to that particular coflict.