I've seen (to me, bizarre) gloating over 3,700 people losing their jobs. While it's true that probably any large company could stand to cut 5% or 10% of its headcount, the cuts at Twitter were so deep that they had to have shed some real talent.
I've been in the valley for a long time now, and while I don't have any particular expertise or experience that will tell me what will happen to the former Twitter marketing folks, or sales staff, or admins.... I can tell you exactly what will happen to their experienced engineers. Come Monday morning (or realistically, Sunday night) recruiters will be bouncing off the walls trying to get those former Twitter builders to come work for them.
Silicon Valley is a strange place, and is really a bubble in some ways... and one of the ways it's a bubble is the employment opportunities for experienced people with technical skills.
For those recently unemployed ex-Twitter folks with any background in full-stack, or high performance back-end, or cloud deployment/security, or very large scale DMBS, or heterogeneous computing, or HPC, or machine learning, or CDN, (and probably a lot of other areas I haven't even thought about)... those folks will take their three months salary and be unemployed for exactly as long as they feel like.
If you're one of those yokels who's getting a good yuk out of highly skilled people losing their jobs, you are perfectly free to behave as you wish.... but in between knee-slaps and guffaws... consider teaching your children how to make machines do useful things.
Or, you know... how to read a textbook.
(Nothing here should be taken as dismissing the stress of losing a job, very especially for those folks with an H-1B)