Yes, in this case, you do need to update everything at once. At least for a given aiport. All it takes is one plane, helicopter, fire truck, or baggage transport vehicle to screw with the assumptions of the system and jeopardize safety.
No, computers aren't necessarily faster, assuming we want to achieve autonomy on the ground. Note that the average human reaction time to visual stimulus is about 250ms. Achieving this on a plane would require a great deal of cameras and sensors that would not only need to stay clean, but capable of withstanding pressure changes, high velocity winds, the occasional unfortunate airborne debris, etc. Then there is the processing power to both process each input in real-time (per plane) and train it on real-world data to recognize a variety of scenarios to act upon (per model and perhaps configuration; AA alone has about 11 active aircraft types across 953 planes). Contrast this with Tesla's investment for approximately 6 models. [1]
Achievable? Sure. Cost-effective and sustainable with current tech? Doubtful.
It's hard to know what that is. TCAS is a great example of an obvious solution to mid-air collisions - two devices seamlessly negotiate for one plane to go up, the other to go down.
One I can think of is an electronic runway "lock". ATC mark the runway as locked to a particular aircraft. The landing aircraft checks at minimums whether if the runway is locked to any other aircraft. It's harder to know how to prevent incursions at ground level, but it could be a beacon near the runway threshold and intersecting taxiways, flashing a warning in the cockpit of the taxing aircraft if an aircraft on final holds the lock. A pilot could still disregard it. Sometimes two planes can share the same runway, such as a plane lining up while another vacates, which adds further problems.
Runway Status Lights (RWSL) are close to what you're describing. If surface surveillance radar detects that a runway is occupied, it turns on red warning lights at the runway approach end and at the hold-short bars.
The nice thing is that the entire system is ground-based, no additional equipment needed in the aircraft.
However, it's complicated/expensive, so only a handful of airports have it installed.
I think you might be way underestimating number 5.
While on the first hand your point sounds very reasonable, in practice it may have more adverse effects than we may think and make the whole system more unsafe.
No, the question is what authorities and regulators conclude, after this incident is properly investigated, regarding improvements and risk mitigation measures have to be put in place. Aerospace regulations are written in blood, and almost-blood, not in public outcry.
You don’t need to update everything at once.
If anything is able to react within seconds, it’s a computer.