tczulu,
Sure that would be an issue until such time as the plane’s computers were talking to the ATC computer...(admittedly more likely to start with the big commercial operators than Mr/Mrs C172).
PLANE determines low fuel. PLANE informs PILOT and ATC.
PLANE determines viable options - diversion airfields/priority approach etc and offers to ATC.
ATC determines which options could “fit”, or be made to “fit”, and offers these back to the PLANE.
PLANE offers PILOT viable solutions.
PILOT selects appropriate solution i.a.w. operator protocols and informs PLANE & ATC.
All in the blink of an eye.
[Where “PLANE”, “PILOT” and “ATC” are all computers.]
Pie in the sky? Sure, in today’s world but I reckon that’s where system architecture is heading - at first by “assisted decision-making” with humans remaining in control of the decisions.
From there it’s a small leap to leaving the computers to take the decision, but monitored by human with executive authority to intercede.