The primary forbearance program people talk about only applies to loans held by Fannie and Freddie, which are government-sponsored entities. I'm not sure of the financial situation at Fannie and Freddie, but the government will bail them out if they start coming up short on cash.

It's also worth noting that the amount owed on a loan keeps going up while in forbearance, so the homeowner does have to pay that money (plus interest) back eventually.