Your iPad Air2 is capable of update to iPadOS 15.7.7. The Air2, as you may be aware, cannot be updated to iPadOS 16.x.
Apple has just released a Rapid Security Response update, iOS/iPadOS 16.5.1(a). Rapid Security Response updates are a new feature of iOS/iPadOS16 - this feature not being available for iPadOS15 or earlier. Until iPadOS15 itself receives a point-update, if affected by the specific WebKit exploit, the issue will remain unpatched at this time.
The iPad Air2 and mini4 still benefit from periodic Security Updates. However, given that there devices are now within their twilight support period, if you wish to enjoy iPadOS16 features (including access to Rapid Security Updates), you might wish to consider replacing your existing iPad sooner rather than later.
As for when new iPad models are released, contributors here cannot comment. Apple does not pre-announce new models. Beyond publicly released information, contributors here have absolutely no insight into Apple’s product development or release roadmaps. The Terms of Use that govern participation within the Support Community disallows any speculation as to future products.