After working with and around writers for almost three decades (gulp!), I've noticed a trend: When writers are "between opportunities," most are dead in the water as to where to turn for their next writing gig.
Whether looking for a job, a client, or a writing assignment, it's vital to know who's buying what you're selling in your market segment. Otherwise, every time you market yourself, you're reinventing the wheel--looking for new contacts, creating appropriate collateral materials, etc.
If you want to make a break with the past and move to a new niche, that's great. But be aware, that in writing, as in every other profession, you're most appealing when you're actively employed. So even if you want to make a job loss into an opportunity to move to something really new, it might be in your best interest to find something short term in your current field while you're investigating your new one.
For writers who intend to remain in their current niche, it's vital to survey the field every once in a while. If you're a business writer, it's obvious that knowing four or five companies from your city's who's who will assist in your next job search, but you should also be aware of two or three recruiting firms who place writers (either full-time or contract) in your area, as well as a couple of journals or magazines who buy articles that you have the knowledge to write.
If you're an entertainment writer, you should be aware of all of the publications (trade, association, and consumer) who buy similar work, as well publicists, music companies, and not-for-profit associations who might want to hire someone with your special talents.
Every niche has a defined arena and known players. The more you know about it, the easier your transition will be from one opportunity to the next.
If you know what you dream for your writing and you take the time to stay up to date with your working niche, your career path will begin to emerge.