That means Zach Sanford has made the opening night roster.
Siegenthaler has been "dealing with a few family issues."
Johansson is recovering from a "lower-body" injury while Wilson is recovering from an "upper-body" one.
The 24-year-old forward spent all of last season with Washington.
'He’s a dominant player now,' Coach Barry Trotz said. 'I think he’s got a high confidence. It gives us great flexibility to do whatever thing we would want.'
Thomas scored two goals in Kansas City on Wednesday night.
The defenseman was Washington's second-round pick in 2015.
Should Cannata clear waivers, he's projected to be the Hershey Bears' top goaltender.
After Malone played 122 games across two seasons in Carolina, he faces an uphill battle to make Washington's roster.
Chandler Stephenson, Travis Boyd, Tyler Lewington and Nathan Walker were reassigned Tuesday.