Huck
Lockheed's still selling C-130's. .
Strange you should mention C-130's. They were flying in automated formation many years ago at night and IMC. But its easier to clear a set of military transport full of paratroops to do that rather than a set of A330s with litigious SLF. People in the FAA and EASA would have nightmares about it. i
THen of course it actually is not efficient unless you have a formation where all the aircraft are flying to the same destination with the same TOW and the same engines and engine wear. The SLF in all but the lead aircraft would also have to get used to the throttle hunting and the continual vertical and horizontal adjustments.
I can't see it happening when flying the 'business trajectory' with DARP where necessary has been shown to be able to save more than a ton of fuel per Atlantic crossing.