The research says that the UK market reflects the US, where the three US portals also dominate locking out local players.
MSN, Yahoo!, and AOL had a combined UK market share of 26% in 2002 but lost ground as non-traditional portals Google, eBay, and the BBC almost doubled their share.
AOL, with its premium ISP offering, expects to make most money in access, but MSN and Yahoo! rely on advertising for more than 80% of their income.
According to Forrester, 2003 could be tough for MSN and Yahoo!, if they fail to differentiate and continue to offer the same products -- premium email-related services.
Forrester believes that while MSN will use its technology skills to attract advertising pounds, Yahoo! will hit back, using Inktomi technology to grab paid-for searches.
AOL's narrowband users will keep it strong, but only for another year as use of broadband increases.
Hellen Omwando, an analyst at Forrester, said: "NLT World has clawed its way from bankruptcy to being the ISP/portal with the highest number of broadband subscribers in the UK, doubling its traffic share during the year. By charging consumers a low-entry broadband access price of £17.99, NTL World has ensured that 60% of its 1.7m net subscribers use broadband, and it has reduced annual churn from 25% to 13%."
She added: "As its two-way cable broadband base quickly saturates, it will turn to its affiliated digital TV platform to cross-promote traffic and cross-sell non access-related services and content. By contrast, expensive BT Openworld has languished, and its traffic share -- which includes other BT properties -- has remained at about 2.4%."
Going forward, Omwando argues that BT Openworld must pick a price-insensitive niche such as home businesses or upmarket consumers that want to play it safe with the BT brand.
The news is not much better for French-owned ISP Freeserve. Forrester says that although it had the most ISP subscribers two years ago, Freeserve.com has barely broken through the 2% traffic-share barrier.
Also, its subscribers' average 14-minute online session is less than half the 35 minutes spent by users of the US players and NTL World. Forrester believes that Freeserve.com should focus on maintaining its narrowband users -- it has 24% of the UK narrowband market -- and compete by launching functional services like property finding.
"Tiscali and Lycos are still hanging on, but only just," Omwando added. "Tiscali has the same broadband offer as NTL World but crucially lacks the strong brand."
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .