It's a fact now: yesterday, king Albert of Belgium announced his abdication by July 21st this year. His son Philip is the successor to the throne.
He's the first Belgian monarch to end his reign with a voluntary retirement. In the Netherlands, the tradition of ruling till death was broken already by queen Wilhelmina in 1948.
There's a funny difference between Dutch and Belgian abdicated heads of state. In the Netherlands, abdicated monarchs lose the title of king/queen, so Beatrix is now once again a princess. In Belgium they keep their title, so from July 21st, Belgium will have two kings and three queens! (but only one of them will be head of state)
No idea when we will get to see the first new euros.