The on-again-off-again speculation about global beer giant AB InBev buying SABMiller turned on again today with a report by Brazilian news website IG that the two brewers are in talks. Bloomberg, which cited the report in a story today, noted that "analysts downplayed the speculation, saying such a deal would be contrary to recent guidance by AB InBev management. The Budweiser brewer is 'the right size' and is focused on so-called organic growth, Chief Executive Officer Carlos Brito said in an interview with Dutch newspaper De Tijd in July."

But even if a deal were to happen -- and you never know in today's climate -- don't look for Bud and Miller Lite to ever be on the same team in the states. It's highly doubtful that antitrust regulators would let the two brewers join forces in the U.S., where they would control more than 75% of the U.S. beer market as a combined company. (AB InBev's share today is 47.9%, while U.S.-based MillerCoors, which is partially owned by SABMiller, has 28.9%, according to shipment data from Beer Marketer's Insights.)

The most likely scenario, analysts say, is that the newly merged company would have to unload SABMiller's 58% financial stake in MillerCoors, possibly to Molson Coors, which owns 42%, but has 50% voting share in the joint venture.

What would that mean for ad agencies and marketing? Hard to say, but perhaps not much. It's conceivable, perhaps even likely, that Molson would allow the 9,000-employee MillerCoors unit to operate pretty much as usual. At present, MillerCoors uses DraftFCB for its two biggest U.S. brands, Miller Lite and Coors Light. AB InBev is reviewing agencies for its biggest brand, Bud Light, which has used a variety of agencies, including DDB. Bud is handled by Anomaly .

The two giants have less overlap internationally, meaning there would be fewer anti-trust concerns. "Rarely are the No.1 and No. 2 global leaders so complementary on global footprint," Credit Suisse said in a note today, summarizing a more comprehensive report from February in which it noted that "we do not see concentration of market share as a significant issue in other overlap markets such as Russia, Ukraine, the UK; we would expect those markets to be sources of synergy savings."

And saving money is the key to profitability in today's global beer environment, in which brewers are having trouble making organic gains in depressed developed markets.