The title-holders will have to submit their final 23-man squad including three goalkeepers on June 4. However, the Bayern Munich goalkeeper will be monitored during the training camp, reports Xinhua news agency.
Joachim Low has told Manuel Neuer he must gain match practice if the Germany captain is to be part of his country's World Cup defence.
Reus, meanwhile, finally has a chance to play in a World Cup, having returned to form and fitness at Borussia Dortmund since his comeback from injury in February.
The Bayern Munich goalkeeper has not played since suffering a recurrence of a fractured foot in September, restricting him to just four appearances since the initial injury in April of past year.
Pirates Top Giants 6-5 For 5th Straight Win
Taillon is 0-3 in five starts since his gem April 8, when he threw a one-hit shutout with seven strikeouts against Cincinnati. National League Central and over is 10-4 in San Francisco last 14 overall and over is 10-4 in San Francisco last 14 on grass.
Loew also opted to stick with the experienced Mario Gomez as his second-choice striker behind Timo Werner and picked Freiburg's Nils Petersen ahead of Sandro Wagner.
"We had some players on the pitch who had the opportunity to show themselves at this level - they did not take it", midfielder Toni Kroos said after the defeat in Berlin.
Juventus midfielder Khedira is the only Serie A representative, as Emre Can of Liverpool - widely expected to sign for Juve this summer - is not included.
Germany's first match in Russian Federation will be against Mexico in Moscow on June 17.