I think the death of Twitter has been greatly exaggerated; notice that nearly all of the conversation around it is taking place on the very site that is supposed to be dying.
Departing employees are justifiably angry about the events of the past few weeks, but I think a desire to see Musk get his comeuppance has colored too many people's assessment of whether Twitter can stay running with a skeleton crew while they rebuild internal expertise. Working code can stay running on autopilot for an impressively long time.
A piece of software like Pinboard can stay running on autopilot for a very long time, because it's simple (that's a compliment, not a dig). A piece of software like Twitter, comprised of a bunch of random interlocking services, is much less likely to stay up unattended. All the random stupid shit that might lock up Pinboard once a year (a full log drive, a run of block errors on a storage device, a network hiccup long enough to blow through a timer, &c) happens to all the services; most of these systems aren't aerodynamically stable: once something burps, the whole system oscillates and wedges until someone goes in and unkinks it.
(Maybe this has been my experience over the past 2 years because our team is just bad at this stuff, but when I relate it to other people working on software like this, I mostly get commiseration).
I'm not taking a position on whether Twitter needs 3000 more engineers to stand a chance of running. I think reports of the death of Twitter are also exaggerated, and I remember reading Dan Luu about bloat at Twitter long before Musk expressed an interest. I'm just saying: it's shocking that the service is running as well as it is right now. Some group of people on that team did a lot of stuff right.
I can identify - I left one of my sites (a 20-year old sports forum) ignored while I went overseas for the last ten weeks, and received a few emails towards the end asking if I was OK.