Trebuchet
Penultimate Amazing
I don't think "dead cat bounce" is the proper term here.
A dead count bounce suggests a temporary rise during a period of lengthy decline. Things go up, but its only for a short period before things start to go down again.
I am sure Biden did get some benefit from the other moderates dropping out... but given things like policy alignment, the "not Sanders" factor, etc., I don't think Biden's improvement is temporary.
(Not that its guaranteed he will win the nomination... just that his improvement isn't temporary.)
I think Sanders will do better in the next set of primaries, not because people will be re-evaluating Biden, but because the next primaries involve states that Sanders won handily in 2016... Idaho, Washington, and North Dakota were all states that Sanders beat Clinton by more than 10%.
Washington's previous primary was after Clinton had all but locked up the nom. Not many people voted, and the votes for Sanders were most likely mostly protest votes. Where Sanders actually won was in the caucuses in March. Linky
ETA: Now that we are having a more meaningful primary, next week, I wouldn't be surprised to see Bernie do pretty well.