Naaaah bring back Arnold.
He IS Conan now.
What you must remember is an actor can only go with the material he/she is given. If its not true to the source, is that the actors fault, or the studio/writer/director/producer/costume department/tea lady.
Il give you a hint, NOT THE ACTOR'S.
Arnold didn't do anything wrong, he made the most of the material he waa given and fact is, he did a bloody good job. Sure the films weren't true to the source material with pin point accuracy, or even spear point, but films never are. They take a character, a story, and strip them down to work into a 90 minute to 2 hr film. To get into that, a crap load needs to be lost. So characters becomes shells of the source, only taking on a few characteristics that help push forward the story and the presentation of the film world. In the films, Hyboria was a harsh, evil world with little hope and no trust, a person needed to be strong and/or successful, and able to care for yourself to survive. The world presented was Barbaric to the point of running on carnal instincts. Thats what Conan was in these films, he was carnal, visceral and self reliant.
Yes the real Conan is so much more, but to investigate every facet of Conan's character, you'd need 3 films just about who Conan is, not including an actual film plot with any action or adventure or anything else that make up a film, in it.
Fact is, to really do any kind of real justice to the source material, the new Conan films would need to be LotR-esque in terms of film length and planning. 3+hr films with one running storyline.
But its never going to happen.
This is the biggest problem with fans of source material, they never seem to be able to get their heads around the fact that a film cannot be 100% faithful, it can only relay the general themes and feelings presented.