I've worked in three million+ loc codebases, in PHP, Python and Java. I don't share your opinion that you need static types in these circumstances. You need discipline, modularity, and most importantly you need to have been blessed with gardeners and maintainers throughout the life of a project and not just after a mess has already taken hold.
Did you read what I wrote?
I already said that you need a disciplined team.
Good luck keeping that team together for years to come.
Not sure if you are disputing the fact that keeping code around is a challenge, or not.
