Wait for More Information
As of right now we don't know a whole lot about Apple's plans. That said, if you're interested in a new version of the iPad Air, you might want to hold off on buying a new iPad for the time being.
If an iPad Air 4 is coming, we'll probably hear a lot about it before Apple makes the official announcement.
You can expect rumors and leaks to outline the device's potential features (3.5mm headphone jack, 5G support, things of that nature), and a potential launch date, ahead of time.
We expect iPad Air 4 rumors to pickup in the summer and fall and those rumors will help you make a more informed decision about your next tablet.