Can you be an expert, and actully find jobs, on PPC, SEO, and Copy writing ? I mean, how are you going to do an PPC compain, do the SEO, and write content on one project ? Unless you can. I dont know.
Those tasks are related, so it is possible that someone cross-trained to learn all three. I would consider handling all those tasks for a campaign to be nearly a full-time job. (If I were an expert in all three- I'm not.)