I agree with this. I have said people dismissing Biden are doing so at their own peril. Elections in today's polarized country are won in a hand full of swing states. 80% of the states are just about out of play. More than that, the elections are won by winning the hand full of independent/moderate/crossover voters. Biden represents a choice moderates might go for. He is very popular in Pennsylvania and would probably flip that state. The other far left nut jobs would not find getting support from moderates and independents so easy. I think Trump himself knows this. It's why he has been consulting with his campaign advisers and and asking what they know about Biden's plans for some time now.
The talking heads have been saying that even the DEMS are suprised that Joe's popularity is what it is right now. It's worth noting that historically, the candidate who is "in the lead" in the poll numbers at this point in the race do not wind up being the nominee.
I think if Biden starts to fall in the polls and out of favor he will find a reason he can't run, blaming family or some such. I don't think his ego will allow him to tank too much before dropping out.
It's all good for parlor game talk, though!