This is an old question but I'll share my experiences.
I majored in marketing myself and landed in an SEO position right after graduation. I think the marketing background has improved my writing and sales tactics, and I've seen advertising/PR majors who get into SEO/PPC and are very successful.
I do wish I had some more experience with programming and coding when I started which is something I've had to teach myself on the fly. If you have a thorough understanding of HTML, CSS, PHP and are able to master the technical side of it then you're already a step ahead. It'll make your life so much easier, especially if you're dealing with a large ecommerce site that is going to need changes somewhat regularly. You'll be spending 15 minutes making a change instead of an hour and have more time for content and UX.