Disney will not cave 4 months after closing the parks. They are a financially savvy, solvent company and they just raised about $7 billion by issuing debt securities, giving them a total of over $12 billion in cash to help them through this crisis. They aren't going to burn through $12 billion by July. They also just furloughed about 100,000 people and other employees took pay cuts to reduce costs. With operating expenses cut significantly and over $12 billion on hand, Disney is not in danger of being insolvent by mid-summer. They also have other entertainment segments that don't require gathering large crowds that they can attempt to ramp up to help with revenue. The sing-a-long was a ratings hit and they released Onward direct to streaming for a fee prior to putting it on
Disney+ (which also, of course, costs money). They also moved up the release of The Last Dance on ESPN which was a huge ratings hit and will be playing (and streaming) for the next five weeks. They are also issuing credits and other incentives for guests to re-book WDW/DL trips, cruises and ABD tours, thereby, keeping that cash on hand (if a guest chooses), instead of issuing refunds. I, myself, took a credit to the tune of $3k today from ABD with an early booking discount incentive. Multiply that by however many guests who are taking the credit for tours cancelled (and, thereby, not costing ABD a dime) and that credit is profit for them. Disney has weathered financial crises many times before and will weather this one as well. They aren't going to open the parks prematurely and risk the health of their guests and employees.