One of the advantages to this treatment is that the dramatic unities of the biography bring it full circle back to The Magic Kingdom. So, the exit of the new park would need to tell the story of Disneyland's own creation.
In that way, a guest who visits Disneyland first would understand the story of Walt Disney in California as said story relates to Main Street, U.S.A. (Walt Disney's hometown), whilst a guest who visits the new park first would understand Disneyland as it relates to the story of Walt Disney in California (the creation of Disneyland).
Naturally, any attraction at the exit of the new park should, therefore, feature: conceptual artwork used in the creation of Disneyland; Walt Disney's likeness, preferably in animatronic form; and, imagery related to the "Disneyland" television series, including, especially, "The Disneyland Story".
Ideally, the finale of such an attraction should also include a moment when the gates to The Magic Kingdom are dramatically revealed. (Disneyland is currently lacking a truly spectacular entrance, but using the monorail beam and pylons to erect an elegant peristyle and an appropriate marquee is a necessity that is long overdue.)