Economic development difficulties in the Northeast are much more
serious than we thought .. According to the GDP data of various
provinces and regions released in 2020 .. In terms of per capita
GDP, Heilongjiang is the second to last .. The per capita GDP of
Harbin, the capital of Heilongjiang, is the last of all provincial
capital cities. Not only is it the bottom but the growth rate is
also the bottom. Will be thrown further and further by other
provinces .. It is undeniable that the decline of the Northeast is
a fact .. <https://www.toutiao.com/i6932352497768022532/>

....

So it seems that not only in the 19th century, but also today it
remains to be somewhat a singular area of lower importance against
the true China ("China Proper").

The recent official population statistics <http://reut.rs/3eGCG8g>
also conspicuously show demographic decline in the north-eastern
provinces. Heilongjiang is leading in decline, with a huge 17%
drop for the recent decade, then Jilin (12%). Plus other figures:
Inner Mongolia (3%), Liaoning (3%), Gansu (2%) and Shanxi (2%).

Younger people tend to move out from the area to richer and more
promising provinces (hence, there are many empty buildings and even
dead settlements). "In the hardest-hit areas of the aging of the
three northeastern provinces and cities, the pension funds .. have
been unable to make ends meet and have been in deficit for many
years" <https://bit.ly/3tCPJM4>. Real estate prices are relatively
very low, but since the climate is cold, heating costs in winter
are quite high, which doesn't add attraction to the area. I learned
it by watching and reading a dozen or more north-eastern v/bloggers.
I also notice some of them tend to present their home area as
somewhat an exotic place where are peculiarities their fellow
countrymen may be unaware of or may have some weird beliefs about.
In turn, when I watch these China's north-eastern sceneries, cities
and settlements, it does not look alien to me but rather more like
"another Russia" ;-)

Currently, the Russians are building a few industrial projects in
the Russia far east intended solely for exports to China, which are
expected to be completed within 3-5 years or so. A stable supply of
gas to HL may mitigate the heating costs there, but I think all this
will unlikely cardinally change the regional trends. While Korea
remains split and NK is closed, and Japan is estranged due to its
Atanticist affiliation, there would hardly be a significant economic
and trade dynamics in the Amur area, so that it will likely remain
backyard-like economically.

I think, if the Sino-Soviet split didn't happen the way it did, and
if the USSR and China developed cross-border cooperation instead of
the expensive military buildups at the border, then both the China's
north-east and the Russia's "far east" would be more prosperous
today. And the blockage still persists. The same cited above author
("high-quality creator in the field of history") says unambiguously
in another post <https://bit.ly/3hbBLOs> that China will start taking
Russia's territory as soon as China "achieves real rejuvenation".
As long as such moods and dreams exist and meet with some sympathy in
China, it'd be natural for Russia to avoid too large joint projects
that might make it dependent on China too much. There's a necessity
for more cultural exchange between people, to make them better know
their neigbour as well as their own selves and histories.