While I may personally prefer statically typed language for large code bases, I think people greatly exaggerate the problems of maintaining large code bases in dynamic languages. Python projects such has NumPy, SciPy and Pandas are several hundred thousand lines of Python. Pandas is 250k LOC in Python.

GNU Emacs is 1.5 million lines of LISP code, another dynamic language.

It is ultimately a question of sound software architecture. You don't have to care about how many lines of code is in the libraries you use daily or in the Operating System you use.

In similar fashion any software can be modularized so you only need to concern yourself with your part.