Assuming there are no Manchu; Mongolia and the land that became Manchuria would not go on to be centralized under the Qing dynasty, as the Ming dynasty either falls in civil war or manages to recover and limp on. Is Russia likely to expand into those lands in the 17th and 18th centuries? In our timeline, they didn't really go that far south into Central Asia until later, but there was definite Russian interest in the Amur river basin that was countered by the Qing; is Mongolia likely to be more left alone?
What about demographics? Would Russians, Cossacks, or Polish exiles come to make up more of the population than Jurchens/Mongolians? Are breakoff states like the state of Jaxa in our timeline, likely to form? What about later when, in our timeline, Han migration lead to them becoming the majority in Manchuria and Inner Mongolia; would this migration still happen, or would Europeans be more likely to fill that niche? If it did happen, would that affect Russian control of the region, or upset order in any breakaway states that might have formed?
What about demographics? Would Russians, Cossacks, or Polish exiles come to make up more of the population than Jurchens/Mongolians? Are breakoff states like the state of Jaxa in our timeline, likely to form? What about later when, in our timeline, Han migration lead to them becoming the majority in Manchuria and Inner Mongolia; would this migration still happen, or would Europeans be more likely to fill that niche? If it did happen, would that affect Russian control of the region, or upset order in any breakaway states that might have formed?