This might be a learning experience for you, who knows. You really like him so you are probably not going to stop texting with him.. so it will either continue on like this until one day you guys won't talk anymore or maybe he really wants to be with you. Who knows. Like you said, young people change their minds quite often.. and their BF and GF. Well, some do. It could be that if you end up being with him that he will find another girl to text with. He may always need others to talk with, some people are just like that.
In the end it comes down to what you want to put up with, what you are ok with. You might just get tired of his behavior or you may meet someone else eventually who is actually available.
Good luck!