Model 3 will be on time, and you will be able to buy a base model for $34,999. Average ASP will be about $55k if I had to guess. here is why:
1) Battery output should be online in 2016. They are accountable to panasonic to have their investment producing and using the batteries. They can soak up some extra production, probably, but they risk idling their expensive signature plant.
2) GM has threatened to produce the Bolt in that timeframe. Of course it won't be in volume, and they dont have a charging network, but I really think they will want to be seen as the innovator. If GM sells 10 Bolts before the model 3 is released, the press will refer to the Model 3 as the car that came after the Bolt and that is a bitter pill. In fact, I have to think that is main motivator for GM: to steal some spotlight.
3) The Model X release isn't a good comparison. Model X is late because it can be late. Model S was only a little late and it came out because they simplified where they needed to, and shipped with incomplete software (ahem, sorry, i mean they keep improving it). With Model X, they have the opportunity to get it just right, and they have a signature feature (the door) which is probably a giant PITA. With X, the priority is getting it right, not getting it on time. With Model 3 they are signalling it will be less ambitious, with no equivalent to the falcon door, which I applaud.
4) The internal deadline is probably much, much earlier. Much of the staff could already be on model 3. They are working out the details with manufacturing the X at this point. The designers are on the model 3 right now.
In short, model 3 is less ambitious, more critical, and they have adequate time to go do it.
Edit: I should add they have a much larger team too, though I worry they will run into
Brook's law (larger team could slow them down instead)