I don't think the whole creating one language and every single person in the world learns it as a second language is going to work out very well and the reason is your post specifically. English is in fact probably the language that is closest to what you are looking for because many countries teach it a a second "international" language, but people complain and don't want to have to learn new languages as it is a huge undertaking, especially if the ENTIRE world had to do it.
Eventually I believe that there will be technology that will just directly let us transfer one's thought to another through whatever medium (or language) of they preference. Whether that will be in our lifetimes or not is the bigger question. At least we can hope for Google translate to get better in our lifetimes :)
