I don't agree with my boss a lot of time. Recently he brought up the concern that "what if" something happened to me? He has a solid concern, I told him that it

I don't agree with my boss a lot of time. Recently he brought up the concern that "what if" something happened to me? He has a solid concern, I told him that it would be and is wise to have another developer on par with my knowledge and skill set. He said he doesn't want me to leave (sometimes I question that, because I'm not his deisred "yes" man). I've been on the fence for a long time about whether to leave or not, because of him. I enjoy most everyone else and the product we build/sell and company. After thinking about this more I realized if we do hire someone to cover me while on vacation or if I have an accident... the social norm/aspect/idea of duty and obligation to help and support my fellow co-workers would be lighted on my shoulders... making it easier for me to leave!