The outspoken Del Nido has been one of the main driving forces behind the effort to persuade Real and Barca to adopt a system of collective bargaining and income sharing for TV rights similar to those used in other major European leagues.
Thanks to their colossal individual deals with broadcasters, Spain's big two maintain a stranglehold over TV revenue which helps make them the world's richest clubs by income and they can buy and pay the best players while their Spanish peers are left trailing far behind.
Del Nido, detailing the outcome of a meeting of Spain's professional football league (LFP) in Madrid on Thursday evening, said the group of clubs pushing for change had grown from the original five or six to 13 out of the 20 clubs in the top flight.
"The message is feeding through because we started with five or six clubs and now the situation is changing drastically," he told reporters.
"We have made a great deal of progress, more than we expected, and the number of clubs will continue to increase, to 15 or 16," he added.
"That will mean that we will have to agree a distribution of TV [cash] that is not only fair but also equitable."
Analysts have long argued that Spain needs to adopt collective bargaining or more clubs will follow Real Zaragoza, Real Betis, Racing Santander and others into administration.
However, Real and Barca have shown little sign they are prepared to give up their dominant position and a recent collective deal struck by the English Premier League, which will boost revenue by 70 percent over three years, makes it even less likely they will accept change, the analysts have said.
