This afternoon, I met with an entrepreneur that just recently had a hugely successful exit. Of course, he's already thinking about what to do next, and it doesn't include learning to fly, improving his swing, nor learning Mandarin. He has all sorts of ideas, ranging from Communications to Internet, and even Medical Devices.
Of course, everybody seems to think that if you have domain expertise that has been developed over the past years, you now qualify as a bigger, more experienced expert in the field... you are "the" perfect entrepreneur in the eyes of the VC's.
But.... he doesn't want to do another semiconductor company. Enough is enough. You spend so many years of your life doing one thing, time to branch out, experience new things, "see the world".
There are some famous examples of people that have failed miserably moving from one domain to the next (e.g. John Sculley at Apple Computer), but at the same time, there are great success stories too. Former Gemini entrepreneur, Nahum Sharfman, who was the co-founder of Commtouch ran National Semiconductor's design facility in Israel before starting Commtouch (-- and after he founded Shopping.com). Nahum holds a Ph.D. from Carnegie Mellon University in High Energy Nuclear Physics. I would bet, that his next gig, will be yet something entirely different.
So, what's the conclusion? None really... as entrepreneurs always do, follow your heart. We'll will be there to support you in whatever decision you make. At the end, It's all about believing in the people.