Bloomberg is now reporting that  by the end of this year the State Department will implement a program allowing visa renewal within the U.S. for non-immigrants seeking H or L visa stamping, including first time applicants. Because a valid visa stamp is required to enter into the U.S., the move would allow non-immigrant workers to avoid long wait times at Consulates abroad, significantly streamlining travel. 

No start date or detailed information has been announced for this program; updates to come as they're available.  

UPDATE - 6/27/23 - Following the Republic of India's official state visit to the United States, the White House released a press release late last week which included the following language: "The U.S. Department of State will launch a pilot this year to adjudicate domestic renewals of certain petition-based temporary work visas, including for Indian nationals, who will no longer be required to leave the country for renewal in eligible categories.  The Department of State will implement this for an expanded pool of H1B and L visa holders in 2024, with the aim of broadening the program to include other eligible categories."