"We are back in a mini-bubble era in terms of people expecting a lot of these valuations, but I don't think we'll see the same amount of exits the way we did," Gates said on Friday at the software giant's fifth annual online advertising conference, in response to a question.
He added that companies such as Amazon, eBay, Yahoo and Interactive are here to stay, but over time the boundaries of what those businesses do will get fuzzier.
Gates was speaking to a group of more than 500 ad executives about the future of advertising during the two-day summit, sponsored by Microsoft's MSN service. However, his speech focused only slightly on advertising and more on his vision of the future of technology, centred on the digital home, networked devices and "seamless computing."
Gates' comments follow recent filings for public offerings by several dot-com companies, including Brightmail and Shopping.com. Small technology companies in specialised industries such as search are also fetching high prices. On Friday, Yahoo said it would buy European e-commerce provider Kelkoo for $575m (£318m), and InfoSpace offered $160m for Switchboard. Stocks in Net search companies are hitting new heights.
Speaking about technology, Gates said that the PC platform and Internet protocol (IP) delivery are expanding into mobile and game devices, into the living room and even into the car. "Everything's going digital, and the best example of this is that the (content) production site is all digital," he said.
Gates built on that idea for advertisers, saying that digital distribution of video (and video on demand) will make it easier for marketers to insert ads that are relevant to their audiences. He also emphasised Microsoft's work with cable companies, such as Comcast, to develop interactive programming guides that tailor program listings to viewers better.
"Nobody has the crystal ball on how this is going to turn out, but we're excited about experimenting," he said, adding that relevance and interactivity are going to play a big part in the development.
Gates also talked about delivering the Internet and data into the home. In the United States, cable broadband is dominant, he said, unlike overseas, where DSL (digital subscriber line) connections are the primary way to access the Internet. To remain competitive, cable companies will have to ensure their bandwidth increases and their packages are attractive, according to Gates. For their part, phone companies that provide DSL will need to get more aggressive and appeal to consumers with video stream services.
"The two dark horses with a path into the home are powerline technology and... wireless technology for last mile, like 802.16 or WiMax," Gates said.
He added that wireless technology, as opposed to Wi-Fi, is typically a much broader range technology and will likely to make more of a mark after the next three years.
Gates also talked briefly about the importance of software packages that sit on top of Internet access. He predicted that the future will bring technology that easily recognises handwriting or voice commands.
In the coming years, technologies will deliver advertisements that are interactive, relevant and targeted to people based on their behaviour, demographics or location, Gates said. He added that the industry has to carefully consider the implications of consumer privacy before going forward.
Specifically, advertisers have to strike the right balance between delivering ads and not intruding on surfers. For example, pop-up ads are loathed by consumers and on the decline, thanks to technology that blocks them, he said. Also, spyware -- programs that track PC users' activities without their knowledge -- was "parasitic," according to Gates. "Spyware is trying to turn the PC into a billboard," he said.
At one point, Gates made the audience of pin-striped executives laugh by showing a commercial of himself and other MSN executives discovering a hot new technology, a "pop and fresh" toaster, and becoming so elated that they run down the halls and form a dance circle.
