No domestic cricket can take place until at least August.
An expanded training group of up to 45 is due to be named on Friday.
The governing body still aims to stage a shortened domestic season.
Professional cricket is on hold until at least July 1.
The tournament is scheduled to start on October 18 until November 15 in Australia.
Hales lost his squad berth in last year’s World Cup triumph after news broke that he had failed a second test for recreational drugs.
Brown’s 489 first-class appearances for Gloucestershire put him seventh on the club’s all-time list.