If it could be done cheaply, and maybe some private financing, air rights leasing (or I guess 'ground rights' because it's an inverted station on a ridge), or a donation by Weston or something...I guess. But the only way I see it done is a special one-unit shuttle car used once every 2h, off-peak. And a tail track for it sit idle.
And the valley is not "one park". I'd like it to be. But it's a corridor hacked and allocated to many uses: sewage, gas, highways, expressways, freight/commuter rail, storage, etc. Other than dirt paths and undesignated trails, the public realm and pedestrian connectivity of the valley is sorely lacking.