https://www.cnet.com/news/ipad-air-2019-vs-ipad-pro-2018-vs-ipad-2018-how-they-match-up/

The 2019 iPad Air fits in between the regular iPad announced this time last year and the 11-inch iPad Pro that appeared toward the end of 2018. 

Apple often introduces new products in March. At last year's event, Apple delivered a refreshed edition of its entry-level iPad in addition to some education-friendly software initiatives. That today's announcement was made by press release suggests that the company wants to keep the focus of next week's event solely on its new video streaming service.