Left to be seen if his base still remains intact if ppl start dying in large nos, the lockdown is indefinite, the economy & the stock market goes into a tailspin & there are massive job losses. There's something known as a negative vote. More associated with anti incumbency .That may well help Biden.
Maybe, but Biden comes off as increasingly senile (the deterioration is evident from just last year...but especially compared to years ago) to huge number of voters. Not a crisis-suitable president....it will show up for sure in the debates when Trump can engage him directly...and likely you will see it materialise in the bookie odds after it (likely far more accurate than MSM polling).
I mean one thing Hillary had going for her was her wits/faculties....yet Trump still trounced her in those debates.
As for extended lockdown+contraction, I find that very unlikely...given even the Fed knows it limits (the public debt has already eroded huge amount of that in the last cpl decades). They are going all out for a cpl weeks now...maybe a month at most....to reduce the impact on the health care capacity. After that it will have to be a compromise system balanced with economic needs. But let us see.

