We reported in March of this year that the upcoming Canon EF 70-200mm f/4L IS II was going to be announced this month.
We're now nearing the end of April and we haven't heard anything further about this lens announcement. We have asked around, but for the moment we're just getting silence on the matter.
It's not unusual for lens announcements to move, even at the last minute. The last one to suffer this fate was the EF 16-35mm f/2.8L III, which was originally to be announced in June of 2016, but was delayed until August 24, 2018. The other recently delayed product from Canon was the Speedlite 470EX-AI, which was originally going to be announced in the summer of 2017, but was held off until February of this year.
The lens is coming and the month isn't over yet, but we cannot update you any further on when EF 70-200mm f/4L IS II is going to be officially announced.
I will say that I am pleasantly surprised about how many people seem to be looking forward to this lens.