Sky is falling for traditional media, again.

+ Marketers Threaten To Put Majority Of Budget Online

According to eMarketer projections, Web advertising as a share of total ad spend will reach 7.4% this year, more than 10% by 2009, and at least 13.3% by the end of 2011.

"Shifts among marketers away from traditional media would make U.S. advertising growth flat-line without the Internet," said David Hallerman, senior analyst at eMarketer.

The increased spending on online ads is coming from a mix of additional allocations and budget shifts from other media, and TV may be in for the largest losses. Among the largest companies, 42.4% of marketing executives recently told BusinessWeek that TV would take the biggest hit in ad budgets in the next few years.