The majority of nations (both democratic and non-democratic) today are Republics of some sort. How could this be different with a POD as early as 1900? How could democratic Constitutional Monarchies be the "standard" government choice of the civilized world?
You mission, should you choose to accept it, is to make the majority of the world's nations be Const. Monarchies in 2008. Bonus points if it is as decisive of a majority as OTL Republics are.