I think that had Howard lived ,it's very likely that he would abandoned fantasy , science fiction and horror all together in favor Westerns , detective stories and historical adventure stories. He was a very good story teller and , in time, would have gotten even better and risen even greater heights. But I think it also likely , that he would have come back to writing fantasy in the 1950's and 1960's and beyond and horror and enven science fiction stories (assuming he could get by John W Campbell)Umm - Howard was 30, not 35 (1906-1936)
I think that he'd have continued with Conan while the demand was there, but in the last couple of years before his death, he mainly wrote Westerns. Given the range of the genres he tried, fantasy, boxing, treasure-hunters, straight westerns, weird westerns, etc, who knows? He even wrote what we'd call romance stories (for Spicy Adventures) which were regarded as marginally pornographic at the time...
Conan The Hour of the Dragon his only Conan novel its his only full Conan novel . Its a terrific book considered one the best fantasy novel ever written.Side note: I found an Aussie website that has a lot of Howard’s short stories for free reading. Conan, Kull, Bran Mak Morn, Solomon Kane, weird detectives, weird westerns, straight detectives, straight westerns and comedy westerns. I really enjoyed the past couple of weeks reading them, especially the Breckinridge Elkins stories.
Howard was very good at historical adventure stories.Lovecraft's death would have shaken him up, surely.
I could see Howard writing more weird stories with local color -- Southwest locations -- and maybe trying to write a serious historical novel with a Southwestern locale.