Middlesex won the Twenty20 Cup to reach the now defunct Stanford Series
The England and Wales Cricket Board has unveiled plans for two Twenty20 leagues to be staged in June 2010.
Each league in the new-look P20 will comprise nine teams, with three sides being promoted and relegated.
The new tournament will also determine qualification for the Champions League, involving club sides around the world.
There will be a second 20-over event later in the season based on the current Twenty20 Cup format, which has been played for the past six years.
The top division of the new competition will be formed by the three leading sides in each of the area groups in qualifying for this season's Twenty20 Cup.
ECB chairman Giles Clarke said: "I wish to thank Nigel Hilliard, the Essex chairman, and his working party for all the hard work they have put into the framework of this competition. I am sure it will be another exciting development in the domestic cricket season."
In opting for the two-division format, the ECB rejected the proposal of a competition based in cities, favoured by some county chairman and MCC chief executive Keith Bradshaw.
England all-rounder Andrew Flintoff, whose involvement in the Indian Premier League in South Africa was ended by injury, was also in favour of the idea of having city locations.
"There is a good argument for that," he said recently. "You could base them in Manchester, Leeds, Birmingham and London and get many of the world's best players."
Smaller counties were not in favour of that idea because they felt only Test match grounds would be able to exploit the opportunities for cashing in on the popularity of Twenty20 cricket.
It is still hoped many of the world's leading cricketers will be involved in the two-division plan, but the number of overseas players and general playing conditions will be discussed at a further board meeting.