The northern provinces of Kazakhstan are mainly populated by people who speak Russian. Most of northern Kazakhs speak Russian as a native language, and have poor knowledge of Kazakh. If you see a Kazakh speaking person in Astana, Kostanay, or Pavlodar, then they are migrants. People native to the region north of Sary Arka Uplands ceased to speak Kazakh in 1960-ies.
That happened because of the Soviet”Virgin Lands” campaign (1954-1960) when hundreds of thousands of Russians and Slavs moved into the region and turned most of the steppe into the fields producing wheat and rye. Kazakhs became a small minority of regions population.
Map of European ethnic groups, as a percentage of district population. From Wikipedia.
However Russian colonization of the region started back in 18th century with foundation of Petropavlosk (1752). Peasants started to move there en masse in late 19th century. The land was taken from Kazakh tribes and given to Russian settlers, free of charge.
Many northern districts still have Russian majority. I predict of them will still have Russian Majority in 2040. That’s because Kazakh migration to the region is mostly directed to the city of Astana. This caused this city to swell, in 1989it had less than 300 hundred thousands people, most of them Russians, in in 2016 Astana had 850 thousands people, most of them Kazakhs.
However it is pretty much the only place of the region which is attracting migrants. Most towns and districts of the North, lose population to either city of Astana, or to neighboring Russian Federation.