One thing to remember is there is a new franchise called the Seattle Kraken playing in 2021/2 season.
Of which the Blues have two protection options.
1. 7 forwards , 3 D, 1 Goalie
2. 8 skaters , 1 Goalie
That being said, I doubt both Krug or Faulk will be on the roster after next playing season, Faulk was always rumored to join
Seattle's GM Ron Francis even if D.A. adds to a deal to move him. Armstrong always seems to give away draft picks. Seattle will have lots of cap space to fill, making Faulk an option.