Russia's two main military sites in Syria were the air base at Khmeimim in Latakia province and the naval base at Tartus. Those are both very important for status and prestige reasons for the Russian Federation in its own self-image as sort of a global power. They're also important in terms of power projection in the eastern Mediterranean and North Africa as far south as the Sahel in Africa.
They are Russia's main power projection platforms in that part of the world. Up to this point, it does not look like they're in imminent danger of losing them. I've seen assessments of an evacuation under way. I don't see anything. Yes, there are transport aircraft coming in and out. Yes, they've moved the ships from Tartus offshore a little bit, but I don't see the amount of activity that would indicate a major evacuation is under way.
The Russians are very good at back-channel negotiations. I'm sure that they've been talking to HTS and the other opposition groups the entire time. There was a Syrian caretaker prime minister from the Assad regime who stayed on, so I think Russia believes that it can preserve its access to those bases. We'll see, but I think that's the calculus in the Kremlin now.