The Brazilian could join David Silva by leaving City when their contracts expire at the end of this season.
"There will be a need to regenerate. David has confirmed he is leaving. Fernandinho doesn't know, but its normal when players reach this age and stage in their lives," Guardiola said. "Of course we have to replace them [if they leave].
"I think at the end of the season we are going to decide all the situations; the players finishing contracts, the players for contracts, what we have to do, what we believe is the best for the club, for the organisation next season.
"[If they leave] we don't have to rebuild too much. Three players is not rebuilding a team. That's bringing in seven players, like we did in the second season when seven finished their contracts. Three players is just substituting some positions."