Russia and Iran are expected to have joint a position on the planned peace resolution because their interests coincide. They prefer the restoration of stability and the salvaging of Assad’s regime. It is an issue of image and the preservation of position in the eastern part of the Mediterranean. So they support peace negotiations, but with guarantees for them and their allies, including Bashar Assad himself. Contrary Western countries perceive Assad’s dismissal as a condition of the future peace negotiations. It is why their media-agencies promote the idea that Russia has agree to oust Assad from power. The issue is discussed. but is perceived as issue of а far future.
However, the joint power of Western countries and Gulf monarchies are likely to override the Russian - Iranian alliance. They all want to stop Russia and Iran, as well as Chinese support to Damascus. However this Alliance is not coherent. Qatar and Saudi Arabia want to play a more independent role in the process. Previously, Saudi diplomacy tried to unite the Syrian opposition and legitimize their Islamist proxies like Ahrar al-Sham. Another Saudi initiative is the creation of the so called Islamic Anti-terrorist coalition, which is aiming to label Shia-groups, such as Hezbollah, which fight ISIS and other rivals to Assad in Syria as terrorists. Both initiatives are far from likely to be successful, but can be used by Saudi to raise their stake in negotiations.
Beside Assad’s fate, another contradiction between Russian-Iranian and Western-Wahhabi blocks is the list of participants of the peace process. While Russia and Iran want to exclude from the process hostile radical Sunni Islamists, labeling them as terrorists, the Gulf states want to legitimize them through this process. The West (primarily the US), despite their anti-terrorist rhetoric, is more likely to support their allies in the Gulf.