As someone who pre-dates the public Internet and spent a lot of time dialling in to BBSes when most people thought personal computers were for nerds…
The Internet will fracture, but not break down. What would happen is balkanization of the Internet, with physical areas running their own networks, and a bunch of poor “dark” areas. Some of those networks would likely have low bandwidth interconnections, such that digest data could still spread, much like the early days of usenet and fidonet.
Local culture and tribalism would increase, and information would skyrocket in value. The rich would still have access to, and control, the information. The poor would be left out completely.
So… internment camps and deportations to keep foreigners off US soil, and tariffs to keep foreigners from working remotely.
Have fun having to do ALL the jobs….