Ona, 52, died in his sleep at his jungle hideout near Panguna on Sunday after a short illness.
On Tuesday, Bougainville Copper Ltd (BCL) chairman Peter Taylor doubted Ona's death would make any immediate difference to the prospects of restarting mining.
The Australian copper and gold mining venture - a subsidary of the global giant Rio Tinto - employed thousands and provided a big chunk of the Papua New Guinea government's income after independence in 1975.
But in 1989 Ona and his followers launched hostilites on the island fuelled by landowner anger over benefits from the mine and the environmental damage it was causing.
The conflict dragged on into the 1990s and claimed more than 10,000 lives.
For 16 years Ona stayed in his mountain retreat near the mine, only recently emerging to stage public rallies claiming Bougainville was already independent.
He also said the mine would not reopen until Bougainville's independence was established and he and his followers agreed.
But Taylor said there were many other issues over the mine to be dealt with other than the problems Ona presented.
BCL had yet to talk to Bougainville's new autonomous government, the PNG government and local landowners, he said.
The autonomous government under President Joseph Kabui wants a resumption of mineral exploration and has asked the PNG government to lift the current moratorium and review the Bougainville Copper Agreement Act of 1967.
But Kabui has said any return to mining would follow a plebescite and rather than reopen Panguna, other options could be pursued such as helping landowners collect gold on the mine's tailings.
PNG's government has a minority stake in BCL. Mining Minister Sam Akoitai has said the reopening of the Panguna mine was a sensitive issue and it would remain closed for an indefinite period.
Taylor said the move to review the Bougainville Copper Agreement was welcome and would allow all parties to bring their issues to the table and discuss a possible return to mining at Panguna.
"We can never rule that out when we have an ore body and a mine life of 15 years, he said."
But feasibility studies were expensive and BCL would not undertake such exercises unless the parties involved had approved a return to mining, Taylor said.
"These things won't happen overnight, it's a big operation."
Commenting on Monday's BCL share jump of 17 per cent to 82 cents following news of Ona's death, Taylor said the market was bullish anyway and bigger gains had been made on other days.
At BCL's annual general meeting in May, Taylor said it might not be a case of returning to Panguna to mine but of pursuing the company's seven existing exploration licences for the island.
Source: AAP NewsWire