The Sudetenland was planned to be fully repopulated so that the farms and other businesses could continue as before the expulsion – and so that even the 1945 harvest would go as smoothly as in the previous years. To achieve that optimistic goal, the July 1945 Beneš decrees already contained some sketch how to achieve this outcome.
Just to be sure, the "total revival" outcome was obviously way too optimistic. 3,000 small villages were abolished altogether, 70,000 have self-employed jobs evaporated, lots of associations and family farms were cancelled. Hundreds of churches were gradually collapsing and the clever small industry of the Germans went down. To compensate, lots of new heavy industrial factories were moved to the Sudetenland which meant that those areas became environmentally dirtier than the mainland "protectorate" area.
The crime rate in the Sudetenland went up since May 1945, the end of the war. The conditions for theft etc. were very "favorable".
But the plan was still more than 50% successful. The people who got the ex-German houses were
- 1,500,000 Czechoslovak citizens from the Czech mainland, mostly the poor ones, including Czech citizens who were forced to leave the Sudetenland after the 1938 annexation (out of them, 1.1 million came from the beginning of this operation, October 1945, and two years later; it was the largest intra-national migration wave in the Czech history, of course)
- ethnic Czechs and Slovaks who returned from Romania (where there had been 50,000 just Slovaks at the end of the war, and a large unknown part has returned) and especially 40,000 ethnic Czechs from Volhynia (those were meant to be the "best part" of the new population; Volhynia is in Ukraine now, an area of the Russian Empire that invited Czech settlers in the late 19th century and they received some arable land for free); in total, this included about 200,000 Czech emigrants from previous decades who mostly returned to the Sudetenland
- people who returned from concentration camps, forced labor camps, and armies abroad
- 150,000-200,000 settlers from Slovakia, including a huge portion of Slovak gypsies
- about 45,000 ethnic Hungarians from Southern Slovakia in 1946-47 where the Czechoslovak authorities wanted both to repopulate the Sudetenland and to reduce the ethnic Hungarian influence on the Slovak territory that had been considered a part of the Greater Hungary whenever possible
- in 1948-50, 20,000 Greeks and some Macedonians who fled their homelands after a lost civil war
- add 200,000 ethnic Germans who were allowed to stay (whether it was such a victory for them or not) because they could demonstrate their anti-Nazi activities
Don't forget that 500,000 Czechs could have lived there all the time, even during the war when it was a German territory, and they stayed there. As a result, when the terms are combined, the population of the whole territory once known as Sudetenland (the term was banned at that time, of course, and even today, Czechs use different, more local terms for the mountain ranges etc) was 2.5 million in March 1947.
The diverse and mostly "poor" origin of most of the people in that territory has had implications. The degree of attachment to the land is vastly lower than what the ethnic Germans used to have. The average people who live there today are less skillful and hard-working than the average people before the war. And when one looks at the unemployment rate maps, the higher unemployment areas in the Czech Republic almost exactly coincide with the Sudetenland territory, a fact that is never mentioned and most people probably don't realize what the shape of the high-unemployment areas resembles.
The decreased and decimated population in that area may have contributed about 50% to the visible "shock" that one had when crossing the Czech-Bavarian border, for example, a difference that still exists. The remaining 50% is due to communism itself.
The expulsion of Germans and the repopulation weren't a path to paradise but they were arguably paths away from hell. Due to the ethnic tensions that dramatically strengthened in the 1930s and exploded thanks to the acts during the war, the co-existence of Czechs and Germans would probably have been extremely problematic for many years. The territory has belonged to the Czech lands – governed from Prague – for 1,000 years and because of their general support for the Third Reich, most of the Germans did deserve to lose their homes etc. On the other hand, the expelled Germans really benefited because one was lucky if he could have escaped communism.
All these events have left some scars but they're not capable of igniting new wars. Some descendants of the Sudetenland Germans would probably like to get their real estate back but they're getting weaker and increasingly sensible, too. The descendants of the ethnic Germans who live in the Sudetenland do realize and like to point out the relative decline of the area after the expulsion. But one may say that the area was basically "successfully reunited" with the rest of the Czech lands, perhaps in analogy with East Germany in the wake of reunification. And despite disagreements, the relationships between Czechia and Germany are excellent these days, too.
Some detailed texts in Czech (use Google Translate etc.):