Well, it may well be the plan for Russia to string Turkey along long enough and then devour them. Gaining control of the Strait.
If it brings back Constantinople, then I'm all for it.
Turkey may be too big to swallow—80 million people (almost all Muslims). The Russians’ main interest is in control of the straits but even that would be difficult (Istanbul has about 14 million people and it isn’t the only city along the straits). Greece would have a stronger historic claim on Istanbul (Byzantium/Constantinople) but they would need to evict the current residents—and the entire population of Greece is less than that of Istanbul.