So they've done it. After years of prevarication, non-denial denials and unflattering comparisons with the fiction prize formerly sponsored by Orange, the self-styled "most important literary award in the English-speaking world" has finally ironed out the disabling anomaly – the thorn in its side – that increasingly threatened to undermine its vaunted global significance.

From 2014, US novelists (so long as they are published in the UK) will for the first time be eligible for consideration by the Booker panel. It's a measure of the obsessive and competitive nature of our literary prize culture that this change to Booker's rulebook should seem almost as significant as the nomination of the latest shortlist. Certainly, the award's administrators did not pass up the opportunity to indulge in another spasm of self-congratulatory comments.

Nevertheless – credit where it's due – in the evolution of English-language culture in the contemporary world, this is a small but significant milestone, a recognition that you cannot lay claim to being "most important literary award in the English-speaking world" and exclude the American literary tradition.

This being Booker, the amendment has not come with any serious overhaul of the all-important prize apparatus. Booker has left what its officials call "the basic structure" unchanged. So, no new approach to the judging panel or its chairing. No recognition of a need for younger critics. No increased "transparency" on the model of the former Orange or the innovative Folio prize.

In adjusting the rules governing the submission of novels, Booker has conceded a mild advantage to the big conglomerates over the lively (and smaller) independents. No doubt some will say that this demonstrates the degree to which Booker is in bed with the Big Six (conglomerates). Well, perhaps.

Andrew Kidd, of the rival Folio prize, told me that he thought this amendment to the submission process was "eccentric" and lacking any radical intention. The fact is that the process whereby the annual competition is winnowed has always been flawed and partial. The new entry process is probably going to make authors with an eye on the prize more, not less, likely to stick with the bigger imprints at the expense of the independents.

I will not be the only commentator to discern in the introduction of this headline "US amendment" the timely impact of the Folio prize, whose debut shortlist, drawn from the fiction of the English-speaking world and chosen by its "academy", will appear in February 2014. Literary awards have become big business, and Booker's business (as "the most important literary award in the English-speaking world") is bigger than most. Indeed, if it had not swiftly adjusted the eligibility criteria for its competitors, it would have been in danger of becoming pointless and irrelevant.

Now, for the first time, an influential English cultural icon has acknowledged, de facto, an important cultural truth – namely that the novel in English is every bit American as it is "British". It will hardly come as a surprise to UK readers to be reminded that Lorrie Moore and Ann Tyler are the equal of Anita Brookner, Hilary Mantel and Penelope Lively.

Pace Philip Hensher and Dame Antonia Byatt, this Booker news is not the end of the world, or even a crisis for Booker, though Hensher has found a tame (but anonymous) literary agent to make that claim. One unintended consequence, confined to the US, will be to deprive US readers of a useful window on "British and Commonwealth" fiction.

Yes, the prize will have to adapt, and there will be many cries of of "la patrie en danger". Actually, there's a strong case for saying that, after 45 years, Booker could do with a makeover. It's a shame, in some ways, that its administrators did not go further.

Hensher's other point – that a global Booker will deprive the homegrown writer (aka Philip Hensher) of the potential dividend of winning (or being shortlisted) – strikes me as odd. What could be more shameful, for a serious writer, than to admit that the sails of his or her inspiration can only be inflated by the prospect of success in the annual spin of a roulette wheel described (by the croupiers) as "most important literary award in the English-speaking world".

Here's the bottom line. Booker is a longstanding literary trophy. But no amount of longevity can disguise its essential character: it's a lottery; a sweepstake. It has only a coincidental and fortuitous relationship with literary excellence. As Julian Barnes put it (in a phrase that's almost obligatory to quote in these discussions), Booker and the other prizes are simply "posh bingo".

Finally, in literature, there is only the long game. It's called posterity, a word that, whatever the intonation, means the same in Chicago and Sheffield, Brighton or Baltimore.