Krugerrand
Meow
A few of my friends used to be interested in M3, now are afraid of the long wait time, so they gave up.
Then they weren't really all that interested to start. It's just that simple. If someone really wants something, waiting isn't an issue other than there being a 'specific and immediate *need*' to fulfill in the moment. And like I mentioned, there's ways to cover transportation until one's turn comes up for a 3.
I don't think many car buyers had experience of wating for several years from reservation to delivery except loyal S/X owners.
Most of those S/X owners never waited several years for a car prior to their Teslas either. So the various reasons that had them patiently (and not so patiently) waiting for their cars will be the same various reasons for the next set of new Tesla owners.
The only way TM resolves the issue is to raise billions of fund not only expedite the M3 factory build progress but also increase the capacity to say 1 million cars by 2020. Elon already mentioned "need to rethink production planning", so it won't be supprised to see above happens.
Elon and those at Tesla have shown great capacity to be creative problem solvers. I'm sure they'll work it out like they do everything else.