Comment by hylaride

Some went bankrupt, with Worldcom being the most famous example...though that was fraud. But even those that remained had large amounts of debt that never ends as there's always CAPEX for upgrades to networks to fund (both fixed and wireless). Now a lot of the debt is also from some of them going on media ownership adventures, but even those that didn't eventually got folded into larger companies (eg Sprint).

Most of the ones that survived did so due to being able to pick up distressed assets and at values that could then be profitably monetized - a move that it would not surprise me to see repeat itself in the LLM space (we'll see).