According to Kehl, the current assessment is that Reus will be out for 3-4 weeks. Not so severe to put the WC at risk.
Great news and no need to rush him back. We still lack proper wingers, but hopefully we will start to get some players back. Moukoko needs to start next game, because he is a good finisher and needs the minutes to continue to improve. Consistent game time will also do wonders for his confidence.
If I remember correctly, Terzic had a talk with Moukoko before the season to try and get him to re-sign promising him that he will be counted on this season with more minutes but I really hope that does not mean giving him minutes the last 5-10 minutes every game so it looks like he is keeping his end of the deal. We have seen enough of Modeste to indicate that Dortmund is a level up from his abilities and his contributions )or lack there of) show that. Play Moukoko ahead of Modeste, period!