Faletau, who has won a century of caps for Wales and played for the British & Irish Lions, is struggling with a calf injury but been allowed to stay behind at home as he continues his rehabilitation.
Forwards coach Jonathan Humphreys, however, is confident the 32-year-old number eight will make the World Cup squad.
"His rehab is going well so we are very hopeful he will be available for selection for the World Cup," Humphreys told a virtual press conference on Friday.
"He's coming back so it was just a question of do you drag him out here to do some stuff or can he do it back home, and spend a lot more time with his family?
"So, the decision was made he can do the same rehab process back home. It's looking positive for him."
Faletau could miss Wales’ three warm-up tests against England (twice) and South Africa. The first against England is in Cardiff on August 5th.
"Hopefully he will play but I don't think it's something we'll massively push if he's not 100%," Humphreys added.
"If he doesn't feature it's not going to necessarily rule him out."
