Update: The bill was unanimously approved by the State Senate. Now on to the Assembly:
Great Redwood Trail bill unanimously approved by California Senate
This article also clarifies that the plan also, in theory anyway, provides for trail south from Willits to the Bay Area. The tracks south of Willits would be transferred to the Bay Area's SMART train agency, which would be tasked with building that part of the trail while keeping the tracks intact (rail with trail). North of Willits, the plan seems to be to remove the tracks (rail to trail).