Current situation doesnt provide positive circumstances for strengthening ECO(two of the founding members Turkey and Iran are on opposite camps).If the dispute between Iran and the ''west''would be cleared the ECO would be a good alternative,many countries would join probably the rest of the D-8 to begin with.
Despite political differences, being civilized both Turks & Iranians(atleast they don't kill each other like their nomad neighbors to the south) co-operate more when it comes to trade,economy,commerce, culture & other areas than many in Europe. ECO has the potential of becoming a powerful trading block if not a political entity like EU. It could be a win-win for both Turkey and EU(those who oppose Turkey's membership) ! Both these organizations could increase trade on equal footings.