While the "ideal" concept of opening Neverland to special needs groups, etc., sounds promising; and even a supremely well done state "park" such as the Hearst Castle property set's an example, it still belies the immense amount of discussion, agreement, and work that would be needed.
And opening Neverland to the general public as a park means just that, the "general public". Until there is some sort of way of distinguishing fans/people honestly interested in seeing the beauty and ideals of NVL from morbid curiosity seekers, I just don't know-
And like many others have said, from personal experience, it truly is a narrow 2 lane country "road" that goes on for miles. The entire long road is abutted by personal property. To enlarge the road requires buying property from current owners, or somehow mandating that enlargement will happen. Can the state afford such an endeavor?
The idea of shuttling people from the nearest town to NVL seems viable, then there would be limited traffic to some extent. But has anyone ever heard of a state park/agency offering such services when you're talking miles from a gathering point to the actual entrance to a park? What I can't even imagine is any actual road work being done, the time and upheaval and mess that could potentially take several years to complete, and the neighboring land owners should just say fine, no problem, won't affect me at all.
Private events, charitable events, restricted access for special groups with special needs (physical/low income, etc.), those could probably fly with minimal disruption or actual encroachment to other properties and peoples privacy (and actual access to their property). But a state park and/or general opening to the public on a daily basis, I just can't see it happening readily or in the near future. Until one actually travels that road, sees the surrounding land, the lack of anywhere to expand unless usurping personal property, it may sound like no problem.
Bottom line would also be whether the estate would agree to such a thing at this time, regardless of the percentage it owns. And should the decision be made by Katherine, or wait until the children come of age and can legitimately decide for themselves what they want to have happen with "their" land.
Just my input/opinion.