I would be careful there. The motivations of an imperial dynasty can be different from the motivations of a republic.
The Qing were mainly motivated by security concerns, mainly domestic. They feared rebellion from both the Han and the Hui, so settling Han in Xinjiang was killing two birds with one stone.
The Chinese republic is motivated by economic concerns. Xinjiang has rich natural resources that can yield a wealth of bounty if properly exploited.
The Chinese heartland is crowded, but not overcrowded. The population density is both a challenge and a resource. China's economic miracle would not have been possible without that density.
The development of Xinjiang is an economic enterprise. Obviously it would be wonderful if the Gobi desert could be turned into an oasis, but the SCMP article glosses over major technical hurdles. For one thing, even if you could divert the head-river 1000 km, you still have to deal with irrigation and evaporation. You also need more than just water for agriculture, you need organic matter. Xinjiang already has some very productive agricultural centers, I can see the number of those centers expanded, but it's not really going to turn the entire desert into an oasis.
I don't think so The Han migration is due to depopulation of Xinjiang caused by Dzunghar genocide perpetrated by the Qing. After rebellion by rebellion finally they say enough is enough they kill every Dzunghar on site, man, woman, child with no mercy.
In order to repopulate the Xinjiang The Qing forced migration of Han, Uyghur, Kazakh and Hui into Xinjiang
They divide the Xinjiang into 2 region north and south
The north is settled by the Han , Hui, Kazakh atc
The south is settled by the Uyghur This division still exist today that is why Urumqi is predominantly Han and Hui. The Uyghur are the migrant here not the other way around.
Qing send their own kin the Xibe to guard the frontier It is a long march to Xinjiang using nothing else but ox cart and horses. You can see it in the museum
They perform splendidly beating the Kossack and prevent Russian from encroaching Qing territory . They are still there today In fact they are the only Manchu speaking people around today.
As to water evaporation the native of Xinjiang find a better way to preserve it it is called Karez
And I don't see why they the could not use the same system only now modernized
Evaporation is not a problem here!
BTW this is not SCMP pipe dream it is initiated by Chinese academy of science and SCMP only quoted their finding. Over the years I see a lot of crazy idea one of them is to blow up the Himalaya with atom bomb to create gap and allowing moisture air and rain into Xinjiang . So this tunnel is the most realistic and doable plan
Nobody said they will built it tomorrow but within 5 to 10 years it will be realized no doubt about that The temptation is jut too much
Water is the essence of life without it there is no farm, cities and factory. so in order to entice more Han immigration . they need to ensure the supply of water as is now the supply of water cannot support large popupation in Xinjiang