Now, the German publication Auto Motor und Sport reports that Halo might not even arrive in 2018.
That is because F1's governing body surveyed the drivers to gauge their opinions, and as of 1 February, a "narrow majority" had rejected the system.
Auto Motor und Sport said the FIA received 16 answers from drivers, with 7 voting against it, 5 for it, and 4 abstaining.
"The FIA is continuing to research alternatives," correspondent Michael Schmidt said.
At the Spobis sport business congress in Dusseldorf, reigning world champion Nico Rosberg said F1 must continue its pursuit of safety.
"It's impressive how much we've improved over the past years," said the German. "But unfortunately, two years ago we lost a colleague which was a severe setback for our sport.
"That's why we must still try to make it better."
And FIA president Jean Todt added: "I would say that formula one is currently the safety category in motor sport. But there can always be small improvements."