If I am going to eat somebody, it might as well be you.
This is acceptable. The prohibition against futurive will is a prohibition against that word in that sense, not the future reference. In any case, be going to in this context is present-focused: it expresses present intention or expectation of a future event.
It might as well be you literally means “You would serve as well as (or better than) another as object of my eating.” In actual use, however, there is no modality or tentativeness here. Might as well in this context announces a decision to accept an invitation or opportunity:
A: Wanna go grab a beer?
B: Might as well.
(Actually, in my dialect it would be “Mought's well. Can’t dance, and it’s too wet to plow.”)
The sentence may be paraphrased “Given my intention of eating somebody, I have decided to eat you.”
If I was going to eat somebody, it ... ?
This is trickier. Was here is acceptable colloquially as a variant of formal were. In some contexts it might express uncertainty or hypotheticality, but in the context of my intention it almost has to express counterfactuality: “I do not at present intend to eat somebody, but if I did ... ”
Consequently, it might as well be you cannot follow this. Grammatically it would be acceptable, but semantically the firm intention it expresses does not suit a counterfactual situation. And since its past-irrealis form (might) is already completely ‘modalized’, it cannot be modalized any further. To the best of my knowledge, even dialects which accept modal stacking will not permit this:
∗ ... it would might as well be you.
So you have to find an alternative expression. The closest I can get to a counterfactual version of the original is something like this:
If I was gonna eat somebody it’d definitely be you.
The pronunciation of the preposition of and the auxiliary verb have are identical in casual speech. We say them as: /əv/.
Basically, "you'd of thought" is a way to try and represent the sound of "you would have thought" in normal speech.
Hope this is helpful!
Best Answer
As is usually the case, the progressive places emphasis on the unfolding action. The practical implications of that fact might become clearer if we talk about what situations might call for the progressive over the simple present.
Let's say we are students lined up to enter the hall where our graduation ceremony will take place in a few minutes. Our friend is not here because she has broken her leg. Which tense are we likely to choose?
Now, by way of contrast, let's say that we are students discussing the graduation ceremony which is to take place several weeks from now. If is very doubtful that our friend will be there with us because she has just broken her leg quite badly. We know that she would like to attend but the nature of the injury was severe and she won't be ambulatory for quite a long time.
Would go places emphasis on the prospective aspect.
P.S. Please note that I say "are we likely to choose". Both of these forms are grammatical. The speaker could frame the statement in either way, reflecting their thought and perspective at that moment.