kinda going off that silver article you posted. i think you can key off biden and bernie. if a month after biden is in his polls are up, he's more likely than not gonna win. if he's down, then look at bernie. if biden is falling and bernie moves over 30% then he's more likely than not gonna win.
if biden falls and bernie is static or falls then it's more likely than not gonna be one of the newcomers. maybe you'll be able to pick out a favorite, or maybe not, but at least you'll have an idea that there's a good chance it'll be one of them.
if neither biden nor bernie moves, then i dunno.