Tau, 26, looks poised to begin life in the Engish top-flight with Brighton after manager Graham Potter confirmed they are working on acquiring his work-permit to bolster their attacking options.
And despite the possibility of losing the Bafana Bafana star Kompany has continued to field Tau as he started against RSC Charleroi and Beerschot since returning from injury.
"Yes, he could leave, and it will be up to the other players, and the next ones, to make up for that departure," Kompany said after the 2-0 win on Sunday.
"If I leave the door open for what remains? Even if there is a one percent chance that he will not leave no, I will leave the door open.
"Anything can happen with the Covid, especially administratively, we know. But Percy Tau's commitment has never been questioned. I did not hesitate for a second to start him because I know very well that he always gives everything."
Tau grabbed an assist in their latest victory that moved RSC into the top-four of the Belgian top-flight but was guilty of spurning three one-on-one chances late on in the game.
But the Manchester City legend refused to criticise his performance as his partnership with forward Lukas Nmecha continued to flourish.
"Percy gave everything and worked well, I saw a good relationship between the attacking players," Kompany admitted. "Ok, he didn't score today, that's how it is."
The former Mamelodi Sundowns star has scored four goals and registered a solitary assist in 12 starts since joining the club in August.