Quoted from blondetall:

There is only one line. When the guys first started taking orders, no money was needed to stand in that line, and the first 250 people to stand there and then pay the money when their machine was ready got one. Then the line got much longer than 250 people, so to try to weed out the people who weren't really interested and only standing there because it was free to do so, the rules changed and it cost $250 to stand in the first 250 spots in that line. Of course some people dropped out, and whoever was behind them just moved forward. Anyone wanting to get out of the line could do so at any time, and their $250 was refunded once the line moved forward and the person who moved up into the first 250 spots paid their money.
Once the guys needed money to actually get started building the machines, the cost to stand in those first 250 spots in line went up to $3,000. Again, some people didnt have the money, or found another line they wanted to be in, so they stepped out of line and everyone behind moved forward. Those that had paid money were refunded once the people now in the top 250 spots paid up. Those first 250 people can still leave the line and get a refund, once the money is paid from the people who moved up.
Right now, we are all just standing in line. There are no machines built, so even those like me who have paid in full don't have a 'unit,' we have a spot in line. Despite people dropping out throughout the years, there are rumors that the line is well over 350 total. It doesnt matter who you are or when you got in line... if you are standing in the first 250 spots, you have paid $3,000 to be standing there. There is no $250 spot anymore, the price to be there went up. Now, once machines are being built and handed out in order of the line, if you get to the front and don't have the full amount to pay, then you'll get your money back when the person behind you does pay in full and take the machine. And it is almost certain that once the first few people in line get theirs and give reviews and people see that it can be done, then more people will get in line just in case people drop out for whatever reason.
There is no non-refundable deposit. Never has been. There is no drop out deadline, only the cost to stand in the first 250 spots has changed. No game is going to not be made or sold because someone wanted it but then dropped out. There are plenty in line who will take it, and every reason for 250 units of a $4750 machine to be created and sold.