The current proposal that's being shopped around as the most likely scenario for a 2020 season includes the DH in both leagues during shortened 2020 and 2021 seasons. And several writers have speculated for a long time that the 2022 CBA will include the universal DH.
From Tom Haudricourt on Twitter:
As has been discussed, this could be a serious boost to the current Reds roster (if we ever see it). Fangraphs agrees, giving the Reds the fourth-highest gain in WAR among NL teams from the new rule, with Jesse Winker as the second-most valuable NL DH:Tom
@Haudricourt
Pending MLB agreement reportedly includes DH in NL for both 2020 and 2021. Then comes new CBA which almost certainly will include it. So, NL is a DH league now.
I've been ready for the universal DH anyway, but suffice it to say this gets me excited.