Assad's staying power is under-estimated. Sure, the West (generally) wants to see him go and his rivals in the Arab community are doing their part to help him make that transition. However, the Syrian state is constructed more similarly to the Egyptian model than the Libyan model; with the military playing a prominent and central role in state formation and stability. And while the Syrian military has suffered from a number of high profile defections, it by and large remains on the side of their governmeent (unlike the large Egyptian military and the small, decentralized Libyan military). The Syrian Army remained loyal to the regime in the past, and I don't see how this situation is any different for them. Without external intervention (whether attacking the regime directly, sustaining the rebelling forces, or enticing the military to defect), the best the uprising can hope for is a negotiated settlement.