I should note that Shannon at one point says there are "14,000" languages in the world, because people when saying there are "7,000" languages in the world are forgetting that sign languages exist — however it is a bit presumptive to assume that there is a roughly equal number of signed languages as spoken languages.
Still, I think this is an intriguing perspective that makes me want to know more about the language dynamics and language politics of Deaf people around the world.
So you're saying you're in favor of Deaf people having a set of common signs to use when communicating with people from different countries, but you don't want this to replace the local sign languages? Because if that's what you're getting at, then that's just International Sign, isn't it? That already exists and is widely used at international Deaf events.