"Well, I mean, somebody else is going to get in that position and do a job for us," Blues coach Craig Berube told reporters.
"That's the way we've got to look at it. We've got players. We're a deep team and that's a good thing. Other guys get an opportunity to get in there now and play."
Thomas went to the dressing room in the first period Saturday after falling hard on his left hand following a collision with Coyotes forward Nick Schmaltz.
Before he was hurt, the 21-year-old scored his first goal of the season to tie the game at 1-1.
In 12 games this season, Thomas has put up a goal and five assists. In a breakout 2019-20 season, the 2017 first-round pick (20th overall) notched 42 points in 66 games.