- Wait, there is a domestic player rule? Since when has that been enforce and what is the rule? I've never heard of it before :P
- Hakimi should be the permanent option down the right (well permanent in such till his loan expires next season). Schulz and Hakimi will be very offensive though, maybe Favre wants to go with 3 at the back?
Sorry, looking at my posting there are some mishaps
The tactical change I am alluding to is of course a formation with 3 at the back which would free up both Hakimi and Schulz to play a more offensive role. Additionally it will of course be Schulz on the left and Hakimi on the right, not sure why I said Hakimi would be on the left.
Concerning a domestic player rule, there is indeed one in place. It has been amended a couple of times since 2005 and since 2009 the rules in Germany are as follows:
12 players in the squad of each Bundesliga team need to be german (Lizenzspieler)
8 players in each squad have to be 'Local Players' which means that they have com from the youth system of a german club. More specifically they have to have played three full seasons at a german club between the ages of 15-21. These players do NOT have to be german.
4 players have to be 'Local Players' to the club meaning they have to fulfill the above criterion for the club they are employed at. They also do not have to be german, for example Pulisic was a local player for Dortmund.
Now you can imagine, that these rules have lead to a few issues for a couple of clubs. In my memory it has most prominently been Frankfurt who have given professional contracts to youth players without them ever even being in a matchday squad. I am pretty sure they have had matches without german players on the pitch, this season Trapp, da Costa and in the second half of the season Rode have been their only german players to see regular game time. Yet if you take a look at their squad you will find that there are a couple of players you have never heard of, most of them from their youth ranks. This is done to abide by the aforementioned rules.
This is why Dortmund might struggle a bit in the near future if they want to avoid being in the same situation. Currently the local players for Dortmund are Pulisic, Schmelzer, Bruun-Larsen and Götze if I am not mistaken (I may well be). Additionally Passlack and Burnic are currently on loan but I don't expect either of them to play at Dortmund next season. Even though Reus has played at Dortmund since he was a kid he spent those crucial years 15-21 mostly at Ahlen and Gladbach so he is not eligible there. This might be one of the reasons Dortmund have always been a bit reluctant of letting Schmelzer go. He is an accomplished player and I probably like him more than most Dortmund fans. But he is also a local player and not a youth prospect whose career you might be hampering by keeping him just for the sake of abiding by the rules.
So with Pulisic leaving and Schmelzer on the way out Tobias Raschl and Luca Unbehaun will be promoted from the youth ranks. Potentially the local players for Dortmund will be Götze, Raschl, Unbehaun Schmelzer/Bruun-Larsen next season.
Looking at the german quota in the event of all of Philipp, Schmelzer, Weigl, Rode, Dahoud, Toprak, Oelschlägel, Schürrle, Toljan, Burnic, Passlack leaving this summer (of course not all of them will transfer but lets just look at who would be left) there would be five german players left: Reus, Götze, Wolf, Raschl and Unbehaun. This would leave seven spots open that need to be filled with german players. Of course a few of the potential outgoing transfers will be kept and some they just will not be able to get rid of. Maybe a few more players will be promoted from the U23 or U19. But generally it would be really desirable to have a core of strong german players in order to not have to dance around these regulations as much. This is why I think taking punts at the likes of Schulz and Brandt does make some sense, even if the risk of them only working out moderately well is definitely given.
Sorry for the somewhat lengthy and Dortmund specific write-up, but I think this is actually a quite interesting aspect of squad planning and the general muppetry
Edit: I am pretty sure there are players in the U23 with professional contracts that I have not listed here so please take the numbers of german players needed with a massive grain of salt.