World Rugby and its leading Unions, already on their knees financially due to Covid-19, could be forced close to bankruptcy by the ticking time bomb of dementia claims.
The damage to ex-players as young as 40 began to emerge this week. But allegations persisted that the game's authorities knew the dangers way back in the early 2000s but did nothing.
Players like England's 2003 World Cup-winning hooker Steve Thompson, ex-Bath and England flanker Michael Lipman and former Welsh international Alix Popham are in the vanguard of claims after individual diagnosis. Ireland captain Johnny Sexton has already suffered several concussions during his career.
Irish rugby legend Willie John McBride admitted: "This was an accident waiting to happen, but I didn't think it would happen so soon.
"Now the game is all about physical violence. It is crazy the way players are running into opponents with their head. And it is frightening we have 40-year-olds diagnosed with this, a terrible thing. It's sad. The Rugby Unions are going to have to sit down and look at their game.
"The game has regressed since professionalism. I would ask, why did they change the game? There is so much physical contact now, even in training."
And the great former British and Irish Lion warned: "We will see more and more of these cases."
The cost of meeting any such pay-outs should individual cases or group actions be proven is potentially alarming. On the back of the crushing losses all Rugby Unions have suffered this year, it could be a hammer blow to many countries.
The IRFU's cash surplus of €28m (£25.6m) back in June will become a debt of €10m (£9.1m) by next summer. IRFU Chief Executive Philip Browne warned back in September the professional game's "very existence" was under threat unless fans could return in huge numbers. There was even a warning that Irish professional rugby could disappear as it became clear Irish Rugby's losses will be more than €30m (£27.5m) because of Covid.
"Irish Rugby's net losses in 2020 are catastrophic," he said.
It is a similar story elsewhere in the UK. The RFU is preparing for a £50m loss over the next 18 months.
The Welsh Rugby Union posted a loss of £5.3m after postponement of the Wales v Scotland game earlier this year cost £8.1m alone. They have borrowed £20m to keep the professional game afloat.
And the WRU estimates a £35m loss of income if the 2021 Six Nations matches have to be played behind closed doors, like the autumn internationals.
There seems little hope of many fans being allowed back as early as February. And recently-announced UK government grants to Twickenham and Cardiff will nowhere near cover all the losses.
Losses of this nature are unknown among the Rugby Unions. They represent a serious threat to the entire future of the game as we know it. The cash crisis is alarming.
Yet when compared with the potential costs of meeting claims from former players diagnosed with dementia, even these figures pale into insignificance.
American Football, immersed in this issue for most of a decade, set up a $1bn (£756m) fund to meet claims. By January 2019, US administrators had approved more than $600m (£454m) in claims for brain damage incurred while playing. More will follow. Four conditions are covered in the litigation: Alzheimer's, Parkinson's, ALS (amyotrophic lateral sclerosis) and dementia.
In the US, retired players can seek awards of up to $3m (£2.27m) for moderate dementia and $1.5m (£1.1m) for mild cases.
The US settlement resolved thousands of lawsuits that alleged the NFL hid what it knew about the risk of concussions. Some in rugby may claim they were unaware of the potential dangers facing players. Yet a book published in 2018 offered irrefutable proof that Rugby unions were warned back in 2004-5 about the dangers of concussion to players under the then laws.
The book, entitled 'The Jersey' which I wrote, quoted the former New Zealand rugby great Sir Brian Lochore saying: "I made the point then that they needed to have a cut-off point below the shoulders (for tackling) to make it safer and eliminate most of this problem.
"But the representatives of Rugby unions said, 'No, we can't do that'. I said, 'I think you are wrong'. It has taken them 12 years to work that out. People were starting to go high and that is very dangerous."
Lochore died in August 2019. He was regarded as one of the shrewdest observers of the sport. But his words of warning, allowed to fall by the wayside all those years ago, had long since been proven right. The game's governing bodies could hardly claim they were not warned.
My requests then for a response were met by silence.
Dementia cases from American Football have found that the required care for victims is hugely expensive, around $100k (£75k) a year. Yet a further 143 recent claims were worth only around $140k (£105k) to each claimant. Some received less.
Thompson, the ex-England hooker, admitted sadly: "I have no recollection of winning the World Cup. And knowing what I know now, I wish I had never turned professional."
The size of the storm about to hit rugby union is enormous.