That's completely unrealistic and unsafe. Even with widespread 5G deployment the cellular network will still lack the reliability necessary to make real-time remote driving feasible. When happens when the network drops packets during a critical maneuver?
Furthermore you can't expect a remote operator to suddenly take over with no context of preceding events and immediately control the vehicle in a safe manner. It takes a little time for anyone to understand what's actually going on.
This plays into the density of towers. 5G has a very limited range unlike 4G. It's going to take years (if not decades) to get to a place where 5G can cover the entirety of the US.
Even if we had 100% 5G coverage it still wouldn't be adequate for a safety critical system. What happens when the tower fails on a hot day because the cooling system broke, or a construction crew cuts the backhaul fiber, or the carrier has an infrastructure failure because someone spoofed their BGP routes?
If level 4+ autonomous vehicles are ever going to work then at a minimum they need to be able to operate safely with zero network connectivity.
Dynamic mesh networks can be a nice supplement but no one has ever demonstrated large-scale reliable operation with mobile devices. And you can't always count on having another vehicle in radio range. So turning vehicles into the network won't make remote control viable.
I think the idea would be to have the vehicle detect that its out of its operating spec, and park until either
a) situation returns to within operating spec
b) remote control comes through
The remote control aspect would be severely limited and intended only to get the vehicle back to a situation within its operating spec. This trades the very difficult problems 'need to immediately control the vehicle in a safe manner' and 'what happens if a remote control is lost' into the difficult problems 'how do I detect I'm out of operating spec' and 'how do I park safely when I'm out of spec, especially if I've just lost remote control'
I frequently drive on rural roads where there are blind curves and no real shoulder (and not much cellular coverage either). A human driver can usually steer a disabled car mostly off the road by going down into a ditch or up an embankment. But it's still not a safe place to be. And autonomous vehicle software is nowhere near being able to handle those maneuvers.
It could be good enough if it’s a backup system only. Then again, probably the only reason the government would be enthusiastic is because these amounts of bandwidth would enable continuously streaming GPS tracked dashcam surveillance from every citizens car.
It's not nearly good enough for a backup system. The whole point of having a backup system is for safety and reliability. You can't build a viable backup system atop an unreliable network.
Furthermore you can't expect a remote operator to suddenly take over with no context of preceding events and immediately control the vehicle in a safe manner. It takes a little time for anyone to understand what's actually going on.