Epic Games has announced in the official forum that patch 1.73 will be released soon. The update v5.30 will be released on Thursday, thus overlapping the start of week 7 in Season 5.
Normally, the new Fortnite Challenges start every Thursday, with the release of Patch 1.73 delaying the start of Week 7 on Friday, August 23rd.
Exact details are currently not available, as soon as we get more knowledge we will report!