The Greed League is not just about a cash grab ... it's a risk / reward strategy.
Football in the classic configuration is one of the greatest risk/reward "games" ever invented. From a business perspective - there are two layers of risk - major performance risk and minor performance risk. Let's take the EPL as an example. Major performance risk = relegation; this spawns a massive financial re-engineering exercise on the whole business to stabilize the business and reorganize for the new restricted cash flow and revenue and cost structures. Minor performance risk = league position; this impacts profitability based on league position and media revenue distributions allocated based on that. Minor performance risk is a season by season event. Minor performance risk can be also be impacted by cup runs etc. A club can budget their business profitability - as does Celtic - by presuming an annual foray into the ECL. No ECL ... oh shit.
The Greed League people don't have the stomach for the risk/reward of the people's game. It's hard to manage an investment portfolio with such volatility and there is no good way to hedge. As a result, they are trying to execute a minimum risk, maximum reward strategy, and everybody else be damned. There is a vast array of externalities involved in their strategy. The Greed League people have not performed a comprehensive qualitative analysis of this nor quantified the risks involved - a full real options analysis would be practically impossible. Looks like they are or were expecting to bully their way through opposition as the 800 pound gorillas on the block. The trouble with being an 800 pound gorilla is that when you find yourself out on a limb, quite often the limb breaks.
Branding - its resilience, acceptance and tarnishment - is one of the greatest risks. If the monicker "the Greed League" sticks then the brand is DOA for a variety of reasons - other brands declining associativity so no sponsorship, audience minimization (eyeballs not watching the broadcasts) out of disgust impacting media value and merchandise value, and so on. Recovery may be possible over time, but this would be a war of attrition with no clear visibility on if never mind when the brand's acceptance would turn around.
Walking it back ... is this even possible. Can the English "Big 6" rescind their letters of intent without penalty. Listening to Gary Neville on MNF, he was of the opinion that since United's Glazier had put his name on a statement that morning, that it's now all out war with Glazier, by hook or by crook, bullying this into existence. And that gave Neville, knowing something of the personality, huge cause for concern as apparently by force of personality and expertise Glazier "always" achieves his goals and the public step-out now locks him in. There is commentary that there are members on boards of many clubs that were against this move. Internal rancor may yet turn individual ships around if sufficient public relations pressure can be brought to bare and sanctions for club (and players and coaches) can be levied as to turn the prospect of milk sour.
I can tell you that as a member of Barca, membership were not informed of this. The presidential election being the dominate issue over the previous months. This move would and is likely to have massive political ramifications within the club. The club's board were fearful of even presenting the idea of a new (complete tear down and rebuild) Camp Nou to membership for fear of a political backlash .... but this doesn't even get an "oh by the way" memo. Laporta was apparently never enthusiastic about the idea ... but here we are.
I think the biggest influences that Whitehall can have is to threaten to rescind immigration and work documents to all foreign players. Clearly, using a purely domestic squad wouldn't make City, United et al attractive to watch never mind competitive in a Greed League replete with let's say the majority of elite players playing against them - City, United et al getting hammered every week is not an attractive proposition. The only way around that would be for the English clubs to play their home matches in European stadiums and therefore avoid any work permit issues - it would require two squads. Imagine how that would go over once fans are allowed back into the stadiums.