You can handle this a few ways. One way would be to simply ask him...."how far into the future?". 2 yrs? 4 yrs? 12 yrs? Put a time frame on it, and also be realistic and know that people argue. It's impossible to be that close to someone and not disagree over something once in a while. Tell him you child needs to have parents that love each other to make that commitment to each other and to the child.
You can also start doing other things. Take a class, teach a class, take a trip with a friend or family member, join a group or a club, dress differently, get your hair done differently, start singing around the house. Little things that don't really mean anything, may get him to wondering what you're up to and to get a little jealous and maybe thinking what life might be like without you.
The botXXXXX XXXXXne, is if he never did/does have an intention to marry you, then nothing can make him propose. If he did have it in his heart to ask you, then he will eventually, no matter what. The problem is trying to know what's truly in his head.
I welcome your thoughts....let me know if you want to talk more.