that's the nice thing about renting in germany. there this would not work, the owner can sell the house but they can't kick out the tenant. so whoever is buying is taking over the tenant. and while you can ask a tenant to move out if you need the house for yourself, that too has to consider the needs of the tenant. if they have kids in school it is almost impossible to remove them unless you go out of your way to help them find a new place and they are not forced to switch schools.