Scott Sumner makes an interesting point.
Taken from what the Keynesian commentators are saying, if the US economy continues on its current course of a slow recovery it means that extreme government budget deficits during downturns are no problem and people were stressing out too much over them. If the economy stalls it means austerity really was bad and quite dangerous.
People like it when their pundits are confident, not accurate. So this little trick is probably more for the pundits themselves, since it is easier to be confident if accuracy is assured no matter what the result.