Premier League, Serie A plan to bring forward summer transfer window's end

In recent summer transfer windows there have been disputes over whether players can continue to be signed even after the leagues have started, with many big teams suffering last-minute losses of key players, with little time to react to cover their departure.
As a result, Serie A and the Premier League have a joint plan to bring forward the date on which the summer transfer window closes to before the start of the domestic leagues, as revealed by Italian league president Ezio Simonelli.
“We want the window to close before the start of the league, same for Premier League. But La Liga will NOT close before August 31st, it looks like the same also for Bundesliga and Ligue1," he said.
However, the Italian president confirmed that they need unanimity with the other three major leagues and that is what is preventing the plan from going ahead for the time being. "We’d need unanimity to make it happen and so it’s not easy":