Just days after "Islamic State of Iraq and Syria" (ISIS) leader Abu Bakr al-Baghdadi met his demise during an October raid by US special forces, the group announced the name of the man who has replaced him as leader.

But the true identity of Abu Ibrahim al-Hashimi al-Qurashi remains shrouded in mystery, and with it the group's strategy going forward.

"We do not know much about him except that he is the leading judge of ISIS and he heads the 'sharia' committee," said Iraqi ISIS expert Hisham al-Hashemi.

But there are even doubts that the man exists at all.

Some suggest the group was caught off guard and announced a name as a holding move, to create the impression it is on top of things.

"The organisation was taken by surprise by the brutality of al-Baghdadi's elimination," said Jean-Piere Filiu, an Arab world specialist at Paris' Sciences-Po university.

"It has since communicated the identity of a successor who we do not know if he truly exists or whether it is a decoy while the process of designating a true successor plays out in Syria and Iraq," he said.

Strategic guidance

"In this world, you cannot keep secret who your leader is, no terrorist group today or yesterday can keep a secret as to how its leadership structure is. No one is that good," said Seth Jones of the Centre for Strategic and International Studies in Washington.

Whether he exists or not, the heir has not provided visible leadership.

Under al-Baghdadi, who also avoided the limelight, ISIS experimented with running a proto-state -- producing school textbooks and creating its own currency.

Since the extremist group was driven out of al-Baghouz, the last patch of Syrian territory it held, in March, it has resorted mainly to guerrilla tactics.

If al-Qurashi is to avoid an internal leadership challenge, he will be forced to step out of the shadows, the experts say.

"There is going to be a tension between his need to assert himself and be effective, and his desire for security," said Daniel Byman, a researcher at the University of Georgetown in Washington.

Opting for the latter could be costly, creating a void for extremist groups to vie for supremacy.

"We already see significant criticisms from other [extremists], who are saying that you cannot really be a caliph if you do not have a caliphate," Byman said. "This person will have a very hard time establishing leadership."

For Filiu, vicious attacks carried out by ISIS affiliates in Egypt's Sinai and the Greater Sahara region are helping to give the central leadership time to reorganise.

A 'turning point'

Robin Simcox, a researcher at the American Heritage Foundation, says a weakened ISIS has little hope of reconquering territory in the near future, meaning its fighters will go to ground and adopt "insurgency" tactics.

"While that makes it a trickier adversary to track down in some ways, it also makes it harder for them to attract recruits in the same numbers as there is no longer a 'caliphate' for foreigners to travel to," he said.

"It also makes it harder to raise funds, as ISIS previously brought in significant revenues through taxation and extortion of those who lived under its control in the 'caliphate'," he said.

For Byman, this is "a turning point for the group".

"But without knowing much about the leader, it is very hard to know which way they will turn," he said.