It has been very noticeable -- like should-be-embarrassingly noticeable -- the change from the first week after the debate (where any pundit who mentioned swapping out Biden, regardless of them being in support of that or not, basically always mentioned that Harris would not be a viable/successful alternative) to just the past 2-3 days where suddenly that perspective is forgotten or forbidden. (for-Biden?)
Remember that meeting of Governors at the white house? I bet they asked all of them if any would be willing to step down as governor to run for president and all of them said no. Now they're out of options.