Could you not build up a network of people who you would trust to do a decent job of maintaining the website after you moved on? Then recommend these others to clients if the need arises.
I know some developers will offer "understudy" type services where the code is always available to at least 2 developers. One will do the majority of the work and the second will simply look at changes incase they need to take over.
I know some developers will offer "understudy" type services where the code is always available to at least 2 developers. One will do the majority of the work and the second will simply look at changes incase they need to take over.