This doesn't represent a single year payout, it represents a hypothetical annual payout of dividends.
If the payout comes later than 2018, then you should pay less for it today. So what year? How much will the earnings be? How will those earnings be achieved (how many cars sold)?
This has nothing to do with a 2018 payout.
Do you know what you are buying when you buy a share of TSLA? You are buying a claim to future profits. You expect to be paid in the future: when and how much? If you can't answer those questions, why are you buying stocks ?
Those people are optimistic because they expect their share of profits to rise in the future.
I'm not looking for a "definitive way", I'm looking for a rational way to assist in pricing a stock. When something can't be forecast perfectly, we should cease forecasting it at all?
I'm just asking a simple question about what you'd pay for the stock, and why.