No reason you can't start your own niche consultancy and utilise your own contacts and industry experience.
If this sounds unlikely, then look through the "experienced hires" sections of the countless consultancies out there to see if your skills set might be useful for their posts.
Freelancing, as far as I'm aware, is more of a possibility if you have very specialist knowledge (e.g. realted to IT) which a comapany might outsource.