To me it means Russell joins the team in 2022 when Bottas moves back to a semi competitive Williams and Hamilton just enjoys the role as a maestro to Russell protege. Who knows where the Mercedes will be after the rule changes but for now they just want to ride out this era with the same pairing. But Russell will need a strong guarantee or contract in place for 2022 otherwise mercedes might lose a clear future World champ and incredible driver to someone else.