This might be slightly true for a small subset of companies, but given that this is clearly about Twitter, you absolutely can't "survive" in any meaningful way. What
is possible without 80% of the engineers is keeping the core services running at the current capacity, with no room for dealing with emergent issues. That's about it, and that's all Twitter has really demonstrated so far.
Forget about new products, forget about improvements to existing products, forget infrastructure work/cost optimization, forget not having major data breaches regularly, forget mitigating large-scale security vulnerabilities(i.e. log4j), forget being able to capitalize on market trends on a useful timescale, and forget about the ability to deal with situations that require more engineering capacity that your company uses on an average day.
Entering "survival mode" and keeping only enough engineering capacity on board to keep the service running on a normal day is implicitly a bet that no emergent events are going to demand more capacity from you than is needed on that normal day. The product might be standing now, but you can't do anything useful with a paralyzed company that's going to topple over the first time it faces a stiff breeze.
Forget about new products, forget about improvements to existing products, forget infrastructure work/cost optimization, forget not having major data breaches regularly, forget mitigating large-scale security vulnerabilities(i.e. log4j), forget being able to capitalize on market trends on a useful timescale, and forget about the ability to deal with situations that require more engineering capacity that your company uses on an average day.
Entering "survival mode" and keeping only enough engineering capacity on board to keep the service running on a normal day is implicitly a bet that no emergent events are going to demand more capacity from you than is needed on that normal day. The product might be standing now, but you can't do anything useful with a paralyzed company that's going to topple over the first time it faces a stiff breeze.