Is is not a possibility to outsource the work and keep hold of your business, acting as a consultant to those websites.
At least with this option you'd keep the door open to potentially coming back to work without giving away your business.
If your business is making a good profit I would select a lucky family member (direct or otherwise) and pass it down. I come from a very family orientated family so I would be looking at family members first.
This all depends on your individual circumstances.