Hi,
1. Americans will be eating cloned food soon.
2. Americans will eat cloned food soon.
How about the difference in the degrees of the certainty?
Well, the simple tenses always seem to me to have more force, more strength. However, I'd hesitate to say the certainty is different here. Usually, uncertainty is signalled by qualifiers like 'I think', 'probably', etc.
How about the difference in the degrees of the speaker's speculation?
Same comment as above. I'm not sure what difference you have in mind between certainty and speculation, but it seems like a pretty slim distinction. You don't seem them as related?
How about the difference in the degrees of the subject's volition?
I'm not sure what you are thinking of by 'volition' here. Do you mean to what degree the speaker wants this to happen?
Roro asked Isn't there any meaning (or subtly encoded nuance) of 'starting,' in #2...?
Roro, I understand why you ask the question, but really, I tend to think any suggestion of 'starting' is present in both versions.
I'm all in favour of using simple examples for this kind of thing. In class, I favour sentences like
1. Mary will be cooking dinner tomorrow evening.
2. Mary will cook dinner tomorrow evening.
The simpler the better, eliminating any words that don't relate to the point at issue or that add any possible complexity, like 'soon'.
Other people may like to offer different opinions on this topic?
Best wishes, Clive