Shell we remove py2 dependence in jupyter notebook?

I saw the new in notebook shows:

    error = """
Notebook 6.0+ supports Python 3.5 and above.
When using Python 3.4 or earlier (including 2.7), please install Notebook 5.x.

Python {py} detected.
""".format(py=sys.version_info, pip=pip_message )

So the new notebook just supports py>=3.5.

And I saw many codes like:

try: #PY3
    from base64 import encodebytes
except ImportError: #PY2
    from base64 import encodestring as encodebytes

Is it time to remove them?:face_with_raised_eyebrow:
I wanne try to do this.:smiling_imp: