Since 2018, Google announces a small number of so-called broad Core Algorithm Updates each year. These updates can greatly affect the organic search traffic a web site receives from Google. A negatively affected web site can lose 30% or 40% of its traffic, pretty much overnight. Other websites can see gains of a similar magnitude. For most web sites a BCAU do not dramatically or even noticeably affect traffic.
The most recent BCAU rolled out on May 4, 2020. Google usually avoids major SERP or ranking shake-ups during the run up to the holiday shopping season, which at latest starts on Black Friday in the United States. If this historical pattern holds, the window for the next BCAU is basically any day between now and the end of October (Halloween). My guess is that it is going to happen no later than October 15, but I think it is going to roll out in September. A September roll out will give Google an opportunity to adjust results that aren't to the company's liking. It will also give the company time to add smaller but significant changes as well as adjust SERP layouts and features.
Can Google choose not to roll out another a BCAU this year? I think the answer to that question is no and yes. As I understand it, the purpose of a BCAU is to improve the quality of search results. It seems odd that Google would decide that it is acceptable to let the quality slide. On the the other hand, everything Google does in search it can probably do differently. In other words, Google might change the way it rolls out updates so that BCAU become obsolete.