When is 5G LTE expected to be available everywhere?

AT&T & Verizon have begun to launch their 5G LTE networks.   

5G LTE still not yet widely available, as it has only begun its launch in certain areas. There may be coverage differences between urban and rural areas.   

There are still questions about the wide-spread use of 5G–including it being available around airports, its voice communication capabilities, and its connectivity when users are in locations where there may be metal, tin, or concrete roofs, dense walls, etc.