Morgan was not selected for England on the strength of an outstanding domestic first-class career though. They clearly saw something in him and expect him to step up his game when he plays Test cricket, but I'm sure they won't follow that process for all selections.
Hildreth is now a more complete performer than he was when he used to cash in at Taunton solely.
Taylor may have the best career, we won't know that for some time yet though, that doesn't mean to say they just throw him in. How he's handled and when he's picked will contribute to how successful he can be.