Okay, but for all modern media at those price tags, the overwhelming majority of the revenue is seen within the first year, often within the first month or even first few days (consider pre-orders on video games— RDR2 reportedly made $725M in its first weekend).

Why should this content be locked up for decades past the point where it has already made 90% of the money it's ever going to make? So the Disney company can have a century's worth of exclusive material ready to go when they launch D+, creating an absolutely impenetrable barrier to entry for an upstart?