Ribery, 33, has not featured since suffering a strained muscle in his right thigh during training on Jan. 31.
Ranieri was sacked by Leicester City on Thursday night, nine months after leading them to the most improbable of Premier League wins.
Varela, 23, joined Eintracht Frankfurt on loan from Manchester United in the summer.
Subotic, 28, joined Cologne on a six-month loan from in January after enduring a difficult 2016.
Javier 'Chicharito' Hernandez discusses his transfer prospects, his time at Real Madrid and talks about life at Leverkusen.