As Michael MacMillan and Seaton McLean cash out, risk-embracing CanWest Global Communications and partner Goldman Sachs & Co. have offered $2.3 billion to buy Alliance Atlantis Communications.

The deal will combine AAC's 13 channels with Global Television to create a new broadcasting powerhouse with two conventional networks, 21 analog and digital specialty channels and a stake in five additional specialty channels.

The deal also sees CanWest Global CEO Leonard Asper breaking up in AAC the product of a historic 1998 merger that combined Atlantis Communications, cofounded in 1978 by MacMillan and McLean, with Alliance Communications, the house that Robert Lantos and Victor Loewy built.

Seizing AAC's specialty channels is also a call to arms that promises an all-out battle between CanWest Global and CTVglobemedia for dominance of Canadian television.

"The strong branding of the Alliance Atlantis channels combined with the reach of Global and CH will result in a very solid competitor to the CTV group and provide us an opportunity to grow not only in television but in our online and mobile activities as well," CanWest CEO Leonard Asper told his own and AAC employees in an internal announcement just before he publicly unveiled his complex pact with Goldman Sachs on Jan 10.

Keen to leave its balance sheet flexible for possible deals in New Zealand and Australia, where it is considering selling off broadcast holdings, CanWest Global is contributing only $132 million initially for a 17% stake in a combined entity.

That leaves Goldman Sachs to cover the rest of the purchase price for the new broadcast entity with a mixture of equity and debt, structured to neither impact nor impede the rest of CanWest Global's operations.

Full marks for audacity, but Asper has a tough path ahead of him. Asper says CanWest Global has an option to buy out Goldman Sachs by 2011. But before that, he and Goldman Sachs will determine their share interests in the combined assets by where the operating profits of the respective Global Television and AAC specialty channels stand on Dec. 31, 2010.

If Global Television is earning more money than the AAC specialties at the time, CanWest Global will grab a controlling stake exceeding 50%. Asper could then buy Goldman Sachs out and spin off the new broadcast entity through a multibillion-dollar public offering.

But if AAC's specialty channels generate more money, CanWest Global's stake will fall below 50%, and Asper's betting-the-farm growth strategy may not pay out.

The stakes are high. CanWest Global's Canadian TV operations in 2007 are forecast to turn out $57 million in EBITDA, while AAC's more profitable specialty channels are expected to generate $151 million in EBITDA.

The process by which CanWest Global and Goldman Sachs can cash out after 2011 will be more fully revealed when the shareholder agreement behind the AAC deal is soon presented to the CRTC and financial regulators.