Italian club Roma want to sign Mahrez and the winger, who helped Leicester win the Premier League title in 2016, says he wants to leave.
Asked if he expected the 26-year-old to stay - after a thrilling Premier League opener - Shakespeare said: "Who knows?
"I think we have all seen the funny business of the transfer window.
"We never know what is around the corner. Riyad has been very focused.
"He came out and made a statement, which we are all aware of, but while he trains and plays and is professional the way he is, he will be considered for selection."
Roma say they remain interested but are also "working on other solutions".
Sporting director Monchi said earlier in the week that the Serie A club made an improved offer - of more than 30m euros (£27.1m) - for the Algerian.
"At the moment, the club is very close to the limit and I believe our offer is very significant," said Monchi.
Speaking to his club's website, he added: "If my memory does not deceive me, the last offer we made would make it the most expensive purchase in the history of the club.
"We are not making any effort to sign the player, but at the moment we are still waiting on a positive result. At the same time, we are working on other solutions.
"He has said publicly [that he wants to leave] but I think he also respects his club, and rightly so."
Leicester boss Craig Shakespeare praised Riyad Mahrez's focus in Friday's 4-3 defeat to Arsenal, despite uncertainty over the Algerian's future.