The revolution in hosting strategy would create a "Euro for Europe," suggested UEFA general secretary Gianni Infantino — and fulfil the wish of its president Michel Platini, who floated the idea in June.
The choice of exactly how many cities and countries will host the 24-team, 51-match tournament is scheduled for the spring of 2014.
"The only thing that is decided is that the concept is changing. This leaves the door open to all countries," Infantino said, adding that 52 of UEFA's 53 national members gave support in recent consultations.
UEFA's executive committee committed to Platini's project despite opposition from his most senior vice-president, Senes Erzik of Turkey, which wanted to host the tournament alone.
Platini's vision is to ease the cost burden on hosts and fans, and give smaller countries an opportunity to be in the global football spotlight.
The France great said he was "really passionate" about the plan during Euro 2012, after seeing how co-hosts Poland and Ukraine had been stretched to finance and complete stadiums, airports and infrastructure costing billions of dollars for just 16 teams.
Though France will go alone to host an expanded 24-team tournament in 2016 — having edged Turkey in a final vote — UEFA believes the demands are too much for one or two hosts during a prolonged economic downturn.
"The economic situation is such that you can't expect countries to invest in sporting facilities that such an event requires," Infantino said. "The fact that the Euro moves from 16 to 24 teams bears an additional burden on a country to host the event."
Infantino suggested that the tournament could allow fans in "10, 12, 15" countries to cheer their teams in matches played at home.
The detailed task of suggesting a format and logistics for the month-long tournament will be studied by UEFA's national team competitions panel.
Infantino hinted that smaller countries which have never hosted a Euro, World Cup or Champions League final could be encouraged in a year-long bidding process, which will be launched in January or March.
Romania, which hosted the Europa League final in May at a new, 50,000-plus capacity venue in Bucharest, will be a strong candidate to host up to four matches.
Countries such as Hungary, Cyprus or Estonia could be given "an impetus to build such a national stadium" housing around 40,000 fans, Infantino suggested
"We hope we can boost national team football with this decision," he said.
Still, major European powers such as England, France, Germany, Italy and Spain will expect to be included. Some UEFA members, whose entire population could fit in such a venue, can be excluded from calculations.
One model format for Euro 2020 has each of the six four-team groups allocated to two cities. Those 12 total venues could then get one match each - completing an allocation of four - in the last 16 and quarter-finals stages combined. A 13th host could then stage the semifinals and final.
Georgia football president Domenti Sichinava told The Associated Press on Wednesday that his country could share group-hosting with Azerbaijan, Belarus, Russia or Turkey.
England has expressed interest in hosting the final stages at Wembley Stadium, while Istanbul is another contender after Turkey was overlooked as the perceived favourite for sole rights to Euro 2020.
The UEFA panel advising on possible formats must look at how many countries could want, or expect, home advantage to create a festive atmosphere.
Infantino said fans would find it "difficult to understand" if their country was a host but its national team played elsewhere.
However, the hosts must be chosen "well in advance" of the qualifying matches revealing the 24-time lineup. Qualifiers would likely be completed up to eight months before the first Euro 2020 match.
"This will have to be thought about," Infantino acknowledged.
To ease travel times and costs for fans, UEFA could look to create regional hubs to stage matches, Infantino said.
UEFA insists the multinational hosting plan is a one-off for Euro 2020, and that the 2024 host will be chosen in a traditional bidding contest.