I think it is a mistake to consider the admittance of Turkey to the EU.
First, it is silly, considering the geographic location of the country. Second, the admittance of Turkey to the EU would completely upset the religious balance of the organization; the admittance of such a large Muslim country to a vast majority Christian organization is only likely to upset the people of the current member states. You could almost say that Turkey has no business joining the EU.
Now, if Istanbul were to break away to form its own independent city state, that would be another issue entirely. You can’t beat the opportunity that such a location presents; and I would admit the city in a heartbeat. I feel, however, that there are more cons than pros in admitting an Muslim state to a largely Christian organization.