Do all hypotheticals use "were" or just counter-factual hypothetheticals

Question

I understand that all hypotheticals that are counterfactual use "Were" because of the subjunctive mood.

1. If I were President, I would enact a great number of new policies. (It's counterfactual because I am not president, right?)

I'm not sure what to do if there is a good possibility of it happening; do I still use "were"?

2. If I was/were going to the store tonight, I'd be sure to pick up milk. (It's not nearly as impossible as the first example)

3. If he was/were at the mall with you guys, I didn't see him (I'm not sure at all about ones like this)

Answer 1

[WARNING: In what follows I discuss usage in "actualization" conditionals—conditionals like your examples, which assert that if the event put forward in the condition occurs then the event put forward in the consequence occurs subsequently. Usage is more complicated in "inference" conditionals—conditionals which assert that the truth of the proposition put forward in the condition entails the proposition put forward in the consequence.]

There is more to this than a was/were distinction.

In this sort of non-past conditional if I was is a widespread colloquial variant of if I were, not a contrasting construction. The contrasting constructions are:

• counterfactual I was/were and factual I am in the protasis (if clause, condition clause), and
• counterfactual I would and factual I will in the apodosis (then clause, consequence clause).

Other things being equal, a non-past open condition—a condition whose factuality is not known—and its consequence are both expressed with the ordinary indicative form; the if is all that is needed to express the uncertainty.

NON-Counterfactual: If I am ... I will

BUT: In this case other things are NOT equal: your use of BE going to in the protasis introduces another twist. You may know already that futurive will is rarely used in the protasis, and the same thing is true of BE going to. These futurives^† are not used to express an open condition:

^∗ If I will go to the store tonight, I will be sure to pick up milk.
^∗ If I am going to the store tonight, I will be sure to pick up milk.

Specifically, these futurives are used only to express a closed condition: a condition known to be factual, or accepted as factual for the discussion at hand.

^okIf, as you tell me, I am going to the store tonight, I will be sure to pick up milk.
^okIf, as you tell me, I am going to the store tonight, I will be sure to pick up milk.

You appear to specify, however, a situation in which the factuality of your going to the store is open. In that situation you employ a simple present in the protasis, with inferred future reference.

If I go to the store tonight, I will be sure to pick up milk.

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^† _{Here and subsequently I specify futurive uses, because will (but not BE going to) has a couple of non-futurive uses which are permitted in the protasis: it may be used to express willingness or assent ("If you will pick up the beer, I'll bring chips") or, with strong emphasis, to express habitual obstinacy ("If you will keep teasing the cat you can't complain if she scratches you").}

Answer 2

Here are the answers:

If I were going to the store tonight, I'd be sure to pick up milk. (It's not nearly as impossible as the first example)

If he was at the mall with you guys, I didn't see him. (I'm not sure at all about ones like this)

The first one is counterfactual and takes "were" despite the possibility as you put it in such with your construction. The second one is talking about something that possibly occurred in the past; therefore, "was" is correct.

Here is how you could make it subjunctive, but it would change the meaning:

"If he were at the mall with you guys, I wouldn't see him (because I wouldn't be at the mall to see him).

This one talks about something that is either happening now or in the near future, but is counterfactual; it does not mean the same thing as your example.