It's funny that nobody has brough up this comparison yet. But really if were talking about Elhokar's worthiness of being a Radiant then how has he not been compared to Dalinar yet?
Remember the person Dalinar was for most of his life was NOT worhty of being a Radiant, he was a brutal warlord who lived for the Thrill. More then that he was basically Gavilar's attack dog, he thought about killing his brother out of jelousy and when Gavilar first made contact with the Listeners he wanted to destroy them. What part of that past indicates that he could end up the leader of the new Radiants?
Not only that, but Dalinar didnt start to become a better person until Gavilar died and he read WoK. Which he did when he was in his fourties. It took something horrible happening to him to finally start to grow past being a pitless killer.
Basically If Dalinar can live the life he did, and be that person he used to be and then still become worthy in his fifties when most of his life is still stained with blood, and the thing that FINALLY pushed him onto the right path and to actually grow as a person only happened seven years ago then Elhokar definatly has a chance. It doesnt have to be soon (Remember there is a 10 year time skip after book five) but something tramatic enough happens to wake him up? Absolutly possible.