Paul Vallely: The Syrians have lost their fear. Is it time for a no-fly zone?

When President Assad finally falls in Syria, will he be shot like Gaddafi in Libya, tried like Mubarak in Egypt, or flee to Saudi like Ben Ali in Tunisia?

On Friday, for the first time, the protests in Syria reached the capital Damascus. The demonstrators on the streets of that nation swelled from tens of thousands to a 100,000 and more. Protesters have seized the opportunity to show observers from the Arab League the intensity of the anger against the regime of President Assad, which has now killed about 5,000 of its citizens. Mr Assad's pledge – to implement a peace initiative involving an end to violence, troops pulled off the streets and political prisoners freed – looks worthless. Indeed, the violence has got worse since the Arab peace monitors arrived on Tuesday.

So is it time for Nato planes to begin enforcing a no-fly zone over Syria? Not yet. The protesters in the capital's suburbs are not alone. Syria has been suspended from the Arab League. The King of Jordan has told Assad to step down. Turkey, hitherto an important ally and trading partner, has threatened to cut off the nation's electricity. The EU has moved to extend sanctions against Assad's inner circle. In Washington, there is talk of increasing support for the Syrian opposition. Even China may not resist sanctions at the UN Security Council this month when the Arab League monitors file their report. Assad's departure is assured, but it could take some time. Russia backs him; last year, 10 per cent of Moscow's global arm sales were to Damascus. Russia's investment in the Syrian economy tops $19bn. But that will hold off the inevitable for only so long.

A barrier of fear has been broken, as the increased boldness of ordinary Syrians on the streets shows. Defections from the Syrian army are said to exceed 10,000. The Palestinian faction Hamas has withdrawn many of its lower-level officials from its headquarters in Damascus. Protesters have been chanting for the execution of Assad, but it might not come to that.

A tiny group of Alawite Shia Muslims make up 80 per cent of the officers in the Syrian army. The ruling elite, nervous about the prospect of a takeover by the Sunni majority, might decide to sacrifice Assad. He could be replaced by his brother Maher, the ruthless commander of the ultra-loyal Fourth Division, the only army unit allowed in the capital. There may be key splits in this elite already; that would explain why its politicians decided to allow in the Arab League observers while its military leaders continue to attack protesters before the monitors' eyes.

If Assad loses the support of the urban and business elites in Damascus and Aleppo, that could clinch his fall. That could happen as the economy worsens. It is bad already. This time last year, moderate economic growth was predicted by the IMF; tourism was high and rising, and new oil and gas exploration was under way. Now drought has pushed a million farmers off the land, and sanctions have hit the banks and the oil sector hard. Fuel shortages and power cuts are routine. One in three men is unemployed. The Syrian pound is worth a third less. The strategic hard currency reserve is being spent. What will happen when it runs out?

Perhaps neighbouring Turkey will intervene or arm the Syrian rebels with weapons. Perhaps Syria will descend into a Lebanese-style sectarian civil war. Then might be the time to consider a UN no-fly zone. But we are some way off that yet.