Assuming reservations are indeed refundable, I think I could make a semi worthwhile argument that Tesla should do the opposite and open reservations right now.
Here's my logic (or lack thereof, you all can decide)...
There's clearly a lot of pent-up demand for this car, however it no doubt varies in intensity levels. I think the constituents can very roughly be grouped-out something like this, sorted in descending order of desire:
1. Non-Tesla owners amazed at what the company has achieved so far, desparate to be a part of it, who have high confidence that the M3 will meet or exceed their expectations at a price point they can handle. They almost want to have that agonizng years-of-blind-faith-waiting experience so that they will feel worthy when meeting the OG Roadster, S and X folk who suffered before them and allowed the 3 to be.
2. Tesla owners happy with their Roadster/S/X and anxious to add an M3 to the portfolio.
3. Non-Tesla owners impressed at what the company has achieved so far, definitely wanting to go EV and this sounds like the one, just waiting for the reveal to see if it is.
4. Non-Tesla owners who think the company is bold/intriguing but still have reservations about whether it's going to survive the cash bleed needed to make it to prime time, M3 is on their this-could-be-my-EV radar, but want to see concrete proof of if/when it's going to happen and if this car will really be all that and a bag of chips.
I think there's a lot of people in Group 1 (me for sure) and maybe Group 2 that would lay down cash today, sight unseen, if that got us an earlier production slot. Most of Group 3 will wait to commit at or soon after the reveal. Group 4 will commit when they feel it's close enough to production to prove that the naysayers are indeed idiots, the company is still doing fine and it's all "real".
Although there is indeed a slight risk of more cancellations if the car isn't what's expected or production doesn't start on time (though the need-to-pay-for-now-running-Gigafactory incentive is a huge one to ensure it does), I think the addtional show of faith and new buzz this would create for the company would be well worth it. And I'm sure the injection of what might be a couple of hundred mil into the coffers, although not hugely significant, certainly wouldn't hurt and should help maintain investor confidence in this dark period where they obviously need to spend a hell of a lot more than they're making to finally build the car that will get them to the "big time".
So, who's in??