I've an impression Western media increase (may be even not deliberately) the functional role of the SCO. It's true that SCO was created to oppose the growing influence of the US in the Cental Asia countries, both economic and political presence of the USA in this region wasn’t in the interests of the biggest members – Russia and China. In its today’s form the SCO it’s mostly a political “forum”, aimed to discuss some problems of the states-members, no more than that. Its aim is antiterrorist activity and the region security. It’s highly unlikely SCO becomes one day a real integration union, with Russia and China under the rule of one “supranation” entity…
Practically impossible.
It's also true that the exercises held by SCO last year put other countries "in the guard", but the reality is that the further "military" oriented evolution of the union isn't in the interests of the members.
It's more likely Russia will try to develop another security organisation - CSTO (includes some former Soviet republics).