This administration has been chock-full of chaos and controversy since the beginning, and the departure of Klain — who’s probably taking the opportunity to distance himself from the worsening classified documents situation — won't change much. Zients will likely be the same conduit between an aging Biden and the Democratic Party's demands.
For the most part, Biden has enjoyed staff consistency, keeping Klain and his entire cabinet until now — marking him and Obama as the only presidents since Ronald Reagan to keep a full cabinet through the midpoint of their term. Historically, it’s normal to make a change of chief of staff at this point in a presidency. Unlike the Trump administration, the Biden White House has been successful policy-wise and stable personnel-wise.
There's a 64% chance that Biden will officially declare his campaign for re-election by Nov. 15, 2023, according to the Metaculus prediction community.