There were many different hypotheses on the outcome of Elon firing 80%+ of Twitter employees: 1. The site would crash and burn the next day. 2. Nothing would change. All those engineers were anyways just sitting around. 3. There would be no immediate impact (servers can run by themselves after all), but the site would slowly degrade over time as institutional knowledge around maintenance, upkeep and all the various s…
Let’s not pretend like Twitter has never had downtime, they literally popularized the “Fail Whale” meme way before Elon was around: - https://www.theatlantic.com/technology/archive/2015/01/the-s...
There's a great 2015 essay by Peter Seibel who was tech lead on their Engineering Effectiveness team:
https://gigamonkeys.com/flowers
I'd guess almost nobody from that era remains at Musk-Twitter.