The Russians probably could have gotten a Russian majority in the two NE Manchurian provinces but we're leery about their chances in the third just because of the huge number of Han living there. The other 2 provinces were still relatively thinly settled even given the large amount of Han settlement that had taken place from 1860 onward.
If Russia had the other two provinces, they've got a lot better agricultural and industrial land to start a population expansion from.
If there is a Boxer Rebellion type event I suspect that there won't be a ton of Han Chinese left in Manchuria given what happened in the 64 villages.