import sys

class MyDict(dict):
    # override popitem()
    # override keys()
    # ...
    pass

def patch_modules():
    dict_type = dict
    for module in sys.modules.values():
        if module is None:
            continue
        if '__builtins__' not in module.__dict__:
            # builtin modules have no __dict__ attribute
            continue
        builtins = module.__dict__['__builtins__']
        if isinstance(builtins, dict_type):
            builtins['dict'] = MyDict
        else:
            # In the __main__ module, __builtins__ variable is a module
            builtins.dict = MyDict

patch_modules()

d = dict()
print(type(d))

d2 = {}
print(type(d2))