Outgoing Cricket Australia boss James Sutherland worries that Test cricket will no longer be the primary form of the game.
The issue is even "top of mind" for the International Cricket Council, who are reviewing the effect of higher-paid domestic T20 leagues in international cricket, says Sutherland.
A day after giving 12-months notice for his departure from the top job, Sutherland said one of the big picture issues for the game was finding a balance between the two forms.
"I have a strong view that they (T20 leagues) need to be managed and regulated in such a way that the best cricketers still want to play international cricket," Sutherland told SEN radio on Thursday.
"So they aspire to that and they're incentivised to do that."
The issue is being reviewed by the ICC and could lead to regulations and restrictions on how many T20 leagues cricketers can play each year.
The Big Bash League has gone from strength to strength since its introduction in 2011, followed by the Women's BBL in 2015.
There are also T20 leagues in Pakistan, India, the Caribbean, Bangladesh and the UK, as well as a new Canadian T20 league which will see the return of banned players Steve Smith and David Warner.
Sutherland says day/night Test cricket is important to finding the balance, as it "allows more fans to watch the games or go to games".
"There's no silver bullet solutions to improving the game, but you can't just love it to death and leave it the way it is," he said.