acceptable

  1. If you decide, what would it be?

Do NES speak this way in the streets, in Britain? (Informal English)

Thanks

What way? I don’t understand what you are asking about.

Is (1) grammatically correct sentence?

Out of context it’s impossible to say. The tenses are quite possibly incorrect.

If the intention is to say ‘If you were the person who was making this decision, what decision would you make?’ then (allowing for the correct context) the sentence might be
formally:
If you were to decide, what would your decision be?
less formally:
If you were to decide, what would it be?
informally:
If you decided, what would it be?

To use ‘decide’, then the sentence should be
If you (are allowed to) decide, what will it be.

Hello Beeesneees, that’s exactly what I thought.

A NES I met here in Bosnia told me that (1) is what would NES say as informal English.
I said it should have been (4).
We couldn’t have agreed.
It was yesterday.
Today I got on my mind your (3).

Huh, is it possible that (1) can be heard in the streets of the UK (in the north of Scotland, for example)? May be, young people doesn’t like the subjunctive mood.

Thanks

Anything’s possible. Not all native English speakers speak grammatically correct English - but it is certainly not the sentence which would be expected, even informally, so your friend is incorrect to indicate that it is standard.

I’d like to start from your (3) and create my additional version (7)

  1. If you were to decide, what would it be?

I hope the (6) would be grammatically correct, even though it’s probably not used much.

  1. Were you to decide, what would it be?

Now I will introduce (7) which in my opinion would be the most informal.

  1. You to decide, what would it be?

So, please let me know if (6) and (7) are acceptable.

Thanks

7 is not acceptable to me, even informally.