The club are currently sat in sixth position having suffered defeat in each of their last four Premier League matches, three of which have come at Anfield.
Speaking to CheltenhamGuides.com, Johnson believes Klopp's success domestically and in Europe with the 2019 Champions League title means he has credit in the bank to survive the season, but that may not hold true in 2021-22.
"I think Klopp's job will be safe, but next year will be different," Johnson said.
"This season you can't talk about sacking him because he's been unbelievable, but unfortunately at this level of football, things change quickly.
"I think his job will be absolutely fine for now but next season will be a different conversation."