Don't Buy If You Need LTE
Do you need LTE on your mobile device? If so, you shouldn't buy the 2019 MacBook Air. There is no LTE option and it's unlikely that Apple will integrate LTE with the MacBook Air anytime soon.
Apple's made it very clear that LTE is for the iPhone, iPad and Apple Watch. While there is a chance that Apple will add a LTE option to the MacBook Air in 2020, you shouldn't hold your breath.
Instead of waiting for the MacBook Air LTE model, embrace using your iPhone as a hotspot or commit to the iPad Pro. You can get the iPad Pro with LTE from Verizon, Sprint, T-Mobile, AT&T and other carriers.