From my first post, in case you didn't read it:

"I will also say..... most of the time when we have a droughty summer, we also get fall rains. So, that may help mitigate the situation.  I don't know what you guys in the mid-west are seeing now - are you still very dry, or are you getting some rain showers?  My guess would be that if you get close to normal fall rain showers, you will be fine.  This will be a "non-issue".

I don't think anyone knows yet what the weather is going to be like this fall.  And from my experience, in seeing localized droughts here, I've never seen an issue with soybean nodulation in the year following a drought. 
If the mid-west does not get any rain from now until next year's planting season, I think you have bigger issues to worry about than whether the rhizobia survive or not.  And if the mid-west DOES get normal rains this fall,  I really don't think rhizobia survival is going to be a big concern.  At least, that's been my experience.