Bayern Munich, Real Madrid, Barcelona, Inter Milan and Atletico Madrid are among the European clubs to have shown an interest in signing Guehi on a free transfer, and he can sign a pre-contract agreement with an overseas club from this month.
“If you’re just valuing sports, everyone in the club will say Marc has to stay,” Glasner added. “The chairman will tell you the same. But it’s not one-dimensional. If you see the financial situation, it’s very important.
“If somebody comes, there will be a moment when the club says ‘now the financial issue is more important than the sports issue’.
“There will be a threshold where the club has to say it will happen – as long as Marc says ‘I want to leave’, because the final decision is always with the player.”
Guehi helped Palace finish 12th last season and win the FA Cup to qualify for Europe for the first time in the club’s history.
The Eagles then won the Community Shield in August, beating Premier League champions Liverpool on penalties, and are 14th in the table and through to the knockout phase play-offs in the Uefa Conference League.
“The chairman rejected many offers in the summer because we want to play a successful season and wanted to win the Community Shield,” Glasner added. “Therefore, Marc is important, and then he rejected the offer.
“The threshold at that time, the money we got offered was not above it. Maybe it was close, but it was not above.”