There's a lot of bad/faulty assumptions being made here and it's causing panic and needless worry.
First, is there a chance BN could go under, yes. But it's always been on the brink.
Second, BN asked for term forgiveness on its invoices (something a lot of companies have been doing). Invoices are coming from publishers, suppliers, and yes, distributors. (This is where the devil lives in the details.) Technically, Smashwords, D2D, PublishDriive, and the others are all sending invoices. They publish to BN through some means, but send an invoice to BN every month for the ebooks sold. Same way Penguin and Random House send their invoices after the books have been delivered.
When you publish direct through BN, it's not invoiced based. As an ebook sale happens, the funds are split automatically, BN takes their cut and the remainder goes into an account that pays authors. That account is supposed to remain untouched. And when BN was public, we knew that account would remain untouched because of Sarbanes-Oxley.
Elliott is a vulture fund. It goes after struggling businesses, but it likes to prop them up and not sell them off in pieces. Elliot acquired BN in 2019 and it was finalized in August of 2019. Elliott is not going to allow its reputation to be slaughtered by stealing from Paul (direct) to pay Peter (invoices). The direct terms are already generous at net-60, most suppliers (whole-sellers) have a net-45 with a discount for net-30. While the direct publishing account might be tempting to someone without scruples and Sarbanes-Oxley, I lean towards trusting Elliott.
In other words, the sky is not falling yet. Asking for term forgiveness isn't something that should be unexpected, and while I blame BN for not communicating with the distributors, I blame D2D and Smashwords for not going back to BN and getting clarification before sending out a massive email that was only going to cause panic. No one can say where or how BN will land after all this, but if you are publishing direct with BN, you shouldn't be worried about not getting paid.