The Washington Post has an article today confirming that Duckworth is on the short list, but advising that she is unlikely to get the nod.
Sounded like their sources from the Biden campaign have indicated that Team Biden is focused on selecting an African-American woman as Biden's running mate, with Kamala Harris as the favorite, but not a lock. Also said that the Republicans are preparing a campaign blitz as soon as Biden does pick his running mate that: 1) will focus on Biden's age making his running mate particularly important; 2) attacking every possible angle related to the running mate. IOW, more than most elections, the hope for Team Trump is to make the campaign about whatever weaknesses they can exploit in the background (or lack of background) in Biden's running mate.