We're told that the announcement for the EF 16-35mm f/2.8L III has been moved closer to Photokina in September, and delivery along with it. That puts 3 lenses in the mix for announcement at Photokina, the EF 16-35mm f/2.8L III, EF 24-105mm f/4L IS II and EF 70-300mm f/4-5.6 IS II. We also expect to see the EOS 5D Mark IV announced.
Delays with lens launches happen a lot, as production is always challenging. For example, the EF 100-400mm f/4.5-5.6L IS II was set for a Photokina announcement, but ended up being delayed a couple of months and was announced in November of that year. The EF 11-24mm f/4L was delayed by about 6 months, as marketing material was already out, but announcement was held back for production reasons.
If anything else changes, we'll let you know.