Geopolitics is dynamic.
Unfortunately, China doesn't really has any other alternatives in Syria, once Assad's government disintegrates. China also has neither the will nor capability to put boots on the ground in Syria to work towards something that will be massively in their favor, so China can only work with whatever they have.
If anything, it might be in Beijing's interests to come with some sort of agreement with whoever's coming to power in Damascus post-Assad and especially their masters in Ankara that China would at least retain its present investments in Syria, in exchange for them to not support extremist adventures into Xinjiang.
However, if Syria descends into Libya 2.0 instead of just a post-2003 Iraq, then there's an entirely different calculus at play. But of course, Beijing-Ankara communications are still crucial.
In the meantime, China should definitely work towards rapidly stepping up its socio-economic presence and influence across Central Asia and West Asia, especially in light of Russia's withdrawal from Syria (and the Middle East in general). This may eventually enables security presence in the region, should the need arises.
Time is of the essence.
