I agree. Now I'm looking at the effects of a modern day Germany with Silesia being a part of it. For that matter, I wonder what a modern day Poland would be like without it.
Smaller. I cannot say that much about Poland besides. However, there would probably less migration from Poland to Germany in the postwar decades- unless Germany changes its policies concerning immigration. OTL, such migration had to be justified by German origins. With a German Silesia, the number of eligible people should be somewhat smaller.
As others pointed out: a more expensive re-unification. Though OTL’s was not crippling (if you think that the whole of West-Germany could enjoy Swiss or Luxemburgian standards of living in a globalized world, I beg to differ), it was not as cheap as Kohl presented it to be. Including Silesia, the whole process might run differently (economically rather than politically) leading to a slower rate of adjustment to West-German standards.
Maybe, with Germany's economic difficulties more pressing, reforms such as the "Hartz-reformen" under Schröder come earlier than in OTL, this might also mean that Kohl's reign ends earlier than in 1998. Rudolf Scharping as Bundeskanzler?
In the BRD, the “Vertriebenen” (expelled) will be a lot less influential. The Schlesier have always been the most vocal and most stubborn organization among them. Silesia being a part of the DDR might also weaken the Sudetendeutsche, as many Germans from Northern Bohemia and Moravia might rather go a few km North instead of hundreds of km Westwards, thus ending up in the DDR (which strongly discouraged "Vertriebenen"-activities).
Silesia itself will probably function nowadays as a bridge between Eastern and Western Europe.
One more things comes to my mind: as a Czech Republic ITTL would almost be surrounded by Germanies, Prague might be less ready to divorce from Slovakia in the 90s.
In David Crew's Consuming Germany in the Cold War, the argument is made that a primary reason for the DDR's rapid absorption/dissolution following the fall of the wall was its inability to reproduce the consumer society being built right on the other side of the Wall. This was due to resource availability (or the lack thereof), relatively (compared to the BRD) low amount of industry/population, and poor management (he cites the curtailing of the New Economic System as a prime example/cause). According to Crew and the contributors, the political repression of the DDR only exacerbated the problems caused by economic mismanagement, and that economics was the primary reason for the DDR so suddenly reuniting with the BRD.
Having Silesia eliminates problems 1 and 2, but does nothing about the economic management strategy of the DDR. It seems that an enlarged DDR just means an enlarged Germany come 1990's. However, a DDR with Silesia may be on slightly more balanced terms with West Germany, which might mean that reunification (which seems, frankly, inevitable) will follow a slightly different path than in OTL. Perhaps more re-organization and build-up of free industry in the East before a formal reunification in the mid-90's?
That sounds like an interesting book! I agree that the economic promises of Kohl's BRD was pivotal in turning the process of re-unification. Very striking is the slogan which appeared in later demonstrations: "Cometh the Deutschmark we shall stay, if it won't come we shall go" [Westwards].
Also, I wouldn't say that by simply adding Silesia problems 1 and 2 vanish (Silesia is not THAT huge in terms of population and industry). The 3rd problem of mismanagement also means (to me) the tendency to "encourage" a brain-drain towards the West.
Also, the German economy works best when it has full access to global markets, as an importer and exporter. That is a basic problem an even larger DDR cannot overcome.
I am sceptical about a slower re-unification. It doesn't exactly make problems smaller. I also do not think that critical decision such as changing the DDR-Mark into the D-Mark at a rate which was suicidal for most of the Easter industry will be changed, as they were anyways decided against economical advice.