I took "There’s not a fine amount of dragons" as a comment they haven't decided on the actual numbers of dragons to have in the game yet, not that they will be infinite.
I don't think that's correct. "There's not a finite amount of dragons" means there is no set limit. In other words, they're infinite. They may have misspoke or had their information wrong, but I don't think that's the case. Now how common they are is another story. Also, they may still leave or be eliminated after the main quest, but until that is achieved... infinite is what that phrase means.