I agree, the keynote has already occurred I don't see an iPad Air 3 coming until fall 2016...
iPads can be released without a keynote.
Remember the iPad 4? It came out mid-cycle (no keynote) and upset many who'd just bought a shiny-new iPad 3. Not only that, but the iPad 4 got it's own storage bumped up to 128 GB (from 64) just a few months after its debut (no doubt upsetting those who'd just bought what they thought was the biggest model)