In first order it's proposed to be an economical union. I don't understand some sceptical attitude to it in this case. I don't like Putin, but this his proposal is only a statement of fact that in future the whole world inevitably will be one economical space. There is nothing bad in it. Everyone who studied economics knows that customs tariffs restrict the development and don't give any benefits to the whole economy of a country. So why not to make a global economical union?
The another thing is a political union. It doesn't have to be done. A political, social and cultural globalization leads only to dilution of folks and their unification as one global folk of cosmopolitans.