Seibold on Friday became just the third coach in the NRL era to be shown the door within the first month of a season, after the Sea Eagles' winless start at home.
Manly bosses will front the media on Saturday, when they are expected to announce an interim coach before their next game against the Dolphins on Thursday.
Seibold's assistant Jim Dymock and NSW Cup coach Brett Kimmorley are the most likely options, with Manly great Kieran Foran only new to the club's coaching staff.
But in the long term, chairman Scott Penn and CEO Jason King have an era-defining decision to make.
Manly had given Seibold a chance to turn things around after a dramatic year saw them finish ninth last season, but ultimately the club has decided to act before 2026 became a write-off.
Willie Peters would likely have been a serious option for Manly, before he agreed to become the PNG Chiefs' inaugural coach earlier this week.
Ballin is known to have the support of the club's old boys, having won two premierships alongside King and served on Des Hasler's coaching staff.
The former hooker is now a Brisbane assistant, but still has close links to the Sea Eagles and would be expected to be interested in the role.
Broncos coach Michael Maguire indicated on Friday that the Broncos would be unlikely to stand in the 42-year-old's way if he wanted the job.
Arthur's previous impact at Manly also shouldn't be overlooked.
He left a lasting impression on several Sea Eagles in his one year as Geoff Toovey's assistant in 2013, with his defensive work helping take them to the grand final.
Arthur is easily the most experienced coach on the market after 10 seasons at Parramatta, before helping turn Leeds around in England in the past two years.
The other potential option is Ennis, who was on Manly's coaching staff as recently as last year while being sized up as Seibold's long-term replacement.
The former NSW State of Origin hooker is now an assistant to Shane Flanagan at St George Illawarra, and insisted on Friday night he had not spoken to Manly.
"It's obviously extremely disappointing for Anthony," Ennis said on Fox League.Â
"I haven't put any thought into it. I am completely and utterly focused on our game, which is an important one for us at the Dragons (against Gold Coast) on Sunday."
For Manly, this decision is crucial.
A changing of the guard looms at Brookvale, with just nine players locked in beyond the end of next season and Manly now 15 years on from their last premiership.
Highly-touted half Joey Walsh has currently been left to develop in NSW Cup and will become a free agent in November if not re-signed in advance.
He, Simione Laiafi, Onitoni Large and Hugo Hart are viewed as big future prospects, with Tolu Koula, Lehi Hopoate and Haumole Olakau'atu all still relatively young.
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