New competitors will come along, readers will change their reading habits, and your organization will continually evolve. Many inexperienced publishers lock themselves into a single strategy and they fall apart when their circumstances change. Look for ancillary profit opportunities. Many publication make most of their profits from special reports, seminars, books, videos and other ancillary products. Plan well before you leap into print.
Publications are relatively easy to launch but hard to maintain.
Make sure you've chosen a subject that you care about and that you're suited to a publisher's lifestyle. The best insurance is to do a lot of homework before you launch learn as much as you can about publishing, study your audience and your competitors, and carefully define your own goals and aspirations. Don't go forward until you've got a long-term plan you can live with. Here are two books I recommend for first-time publishers. You can read them both in one weekend, and you'll learn everything you need to know about starting publications.