Not so long ago there seemed no end to the couplings. In less than two years WPP has seduced Young & Rubicam while True North has fallen for Interpublic's charms. Bcom3, which brought together the D'Arcy and Leo Burnett networks, had barely bedded down before accepting a $3 billion bid from Maurice Levy's Publicis group, already enlarged by the purchase of Saatchi & Saatchi.
Now it looks as though consolidation is moving towards its end game.
Not even the voracious Levy expects any further acquisition activity beyond some small-scale deals intended to plug existing gaps in areas such as PR, direct marketing and sales promotion.
A new global communications skyline has been created. It will be dominated by four "supergroups
- WPP, Interpublic, Omnicom and Publicis - with Japan's Dentsu, ever eager to join the global dance but nervous about slipping up, emerging as a significant bankroller.
Back on the dancefloor, only Cordiant and Grey remain to decide whether or not, in the absence of other suitable suitors, they can make a go of it with each other.
But surely consolidation wasn't really meant to end up this way. Wasn't the whole point of it to align agency offerings to client needs; to create a range of diversified services which would protect holding companies by reducing their exposure to clients when they cut back on expensive above-the-line activity during recession?
What for some has been a logical structural change enabling clients to hold their own in an increasingly complex communications environment is seen by others as having exacted too heavy a price.
They believe consolidation's aims have been subverted, creating a culture that's stifling creativity and innovation while encouraging entrenchment and a predisposition to play it safe.
It may be neat and tidy to have nearly all Procter & Gamble's agencies within a single holding company, but is that necessarily what such clients want?
More importantly, how long before those with the biggest egos refuse to be treated as pawns in the consolidation game and readopt uncompromising attitudes to conflict?
If so, the Publicis group could find itself the target of other network predators as it juggles its own Nestle business with the Kellogg account at Burnett. Meanwhile, will the giant General Motors, a major client of Burnett and D'Arcy, be content to share a holding company with Toyota, whose global account is handled by Saatchis?
Nevertheless, many leading industry figures insist that what's happened has been almost entirely client driven. "The simple truth is that this is what clients have asked for,
David Pattison, the chief executive of the PHD group, claims.
"Not by directly asking but by the structures and organisational shapes that they ask us to work with. Despite what people believe, our industry follows its clients' needs; it doesn't set the agenda for them."
Not everybody else is quite so sure. Chris Jones, the non-executive chairman of Results Business Consultancy, believes clients feel about consolidation the way most of us feel about the wire hangers we collect with our dry cleaning - part of the package but of no further use.
"It's not what they asked for,
he says. "It's simply an inevitable by-product of getting what they really want and need."
He believes there's a simple explanation for client indifference. "The importance of integrated communications is a given. The value of the integrated supply of them is not."
Yet, irrespective of whether clients have driven consolidation or merely been swept along on the tide, the relentless pace of it has left Cordiant and Grey seriously exposed.
Unable to attract big global clients, Cordiant is suffering the consequences of overpaying massively for the Lighthouse group, while Grey shows no sign of a coherent management structure to take over from its septuagenarian chairman, Ed Meyer. The network also struggles to get its margins above single figures. One former senior executive admits: "I get the feeling that Grey is hanging by its fingertips from the top of a tall building - and the wind is starting to blow."
Cordiant, rapidly running out of options since Alain de Pouzilhac, the Havas chairman, publicly declared his disinterest in it, has at least indicated willingness to address its predicament with the appointment of David Hearn as the worldwide chairman of its Bates network.
Not so at Grey, where Meyer's two potential heirs apparent - Carolyn Carter, who runs Europe, and Steve Blamer, the boss of the flagship New York agency - are still said to need to prove themselves.
"Carter could galvanise Grey but there's been no serious attempt to put her in the firing line,
an insider says. "The New York agency hasn't done well but it's difficult to judge Blamer while the US economy remains in recession."
On the face of it, a marriage of Cordiant and Grey looks like a coming together of the Hindenburg and the Titanic. But some industry observers believe a merged network would be greater than the sum of its parts.
For one thing, their shared global client, British American Tobacco, is likely to bless the union. For another, there are some clear synergies; Grey has nothing to match Cordiant's successful 141 below-the-line network or Bates' expertise in the retail and financial areas; in P&G, Mars and Glaxo Smith-Kline, Grey has the kind of FMCG clients Cordiant would kill for. What's more, Grey has the cash Cordiant needs.
"A combination of Grey and Cordiant may not be able to compete at a global level initially,
a mergers and acquisitions specialist says. "But it could provide a solid foundation which could be built on through the acquisition of some strong independent local players."
It remains to be seen whether all this will be enough to force them into each other's arms as the music stops.