That the writers have been able to carry on the central storyline - the Latimers and their ongoing grief over losing their son - over 3 seasons, even amidst a very more prominent storyline this season speaks to how special Broadchurch as a series has been. The finale brings an immense sense of closure to the Latimers, as Beth and Mark now must learn to deal with their grief in very different ways. The writing of Mark Latimer and his grief is done to perfection this season, and it's something close to what we see in Manchester By The Sea.
The stars of this series, amongst the rest of the exceptional cast, will always be Olivia Colman and David Tennant. They have and will continue to have many other roles in their career, but their combined presence in this series has been a gift. They exude grace and humanity in their characters, always striving to do good by other people, even if they sometimes struggle dealing with their own battles (as we all do).
I will never forget Broadchurch, this series and this fictional place and community, and it will always fondly come to mind whenever something vaguely similar to this genre comes along.