King Orrin has to die in order to not become king of alagasia.

King Orrin won't die. He is far too important a character in the Alagaesian universe, but not that important in book terms. Orrin, in my opinion, is the least likely one to die in Book Four. Even less likely than Roran or Saphira and Eragon.

But orrin is the most likely candidate for king after eragon kills galby. Eragon said he wouldn't want orrin to become king. Nasuada should rule alagaisia or roran.

I think the whole point of the story is that it shouldn't be ruled by neither a king or queen. That everyone should rule themselves and the Riders were there to keep peace if they couldn't handle problems by themselves

even in the riders time there was a king wasn't there?

not that I recall. maybe just kings or mayors of each city, but not one over the whole country, and I've read the books several times. the only reason Orrin was set up as king of Surda was to combat Galbatoix

There were kings. Brooding KINGDOM. The kings did have power however they were kept in check by the riders.

your are absolutely right aluminum clock.