それなら

I think that would leave us with nowhere to put the luggage.

If that was the case, you should have told me earlier (implying regret)

If that's the case, you should have told me earlier.

If that's the case, then that's fine.

Then that's fine, isn't it?

In that case, I’ll teach you.

What I arrived at after thinking it through was that.

If that's the case, it might indeed be more efficient.