The out-of-control feud has led to heavily armed members of the garda Emergency Response Unit patrolling the streets of north Dublin after a pitched daylight battle was broken up by officers.
Tensions increased after one faction sent the other mob a disturbing video this week.
Sources say that the gangsters made the video in the same sitting room where murdered 'Marlo' made decisions to kill rivals and order drug shipments from international traffickers.
Hyland and innocent plumber Anthony Campbell were shot dead at the Finglas home of the hood's niece in December 2006. This is not the same property where this week's chilling video was recorded.
A senior source said: "If walls could tell a story, those walls would have some story to tell in that house.
"Hyland sat in that room where he directed operations for a large number of years.
"Now you have Traveller scumbags living there and they make a video in the exact same room where Hyland used to have 'business meetings'.
"The gardai are on top of this and arrests are imminent.
"Making threats to kill is a very serious matter and carries a hefty prison sentence; that's why gardai are going to get to the bottom of this video."
In the video, gangsters spell out several threats, claiming that they would pipe bomb their enemies' homes.
"I'm going to blow away your wives, your girlfriends.
"The pipe bombs are going in through your windows now. Up on top of your children I'll blow them. Ye are all f****** getting it."
Gardai are confident they know the identities of the video threat suspects and the location where they made the film. "We know where we are going on this," said a source.
The Herald has previously revealed that one of the video criminals is from the Tallaght area, while another is a suspected sex offender.
One side has claimed that the video was posted in response to a number of disturbing images involving children being posted online.