Its all relative, a high quantity of orders for a mid or low end part, would be millions, a high quantity on a 5870/380GTX might only be 5,000, and a high quantity of say, 8800 ultra's, might be 500.
With nothing else to produce, what exactly would they be ordering, but ordering, and recieving, aren't close to the same thing.
AS for EOL'ing being a big deal, with a new product coming, its not, but theres still normally some supply somewhere in the channel to keep things ticking till a release, the ideal being the last card being sold the evening before the new cards are released and in stock. The medium case scenario is having too many and selling off several thousand for cheaper than should be, thats not great but not bad. The entirely worst case scenario is running out before your cards out, the longer before the worse, and simply not selling cards.
But this is the problem, when the 5870 launched, the 4870/4850 became the new midrange cards, they were still a viable option.
When Fermi launches, it will be £350-550 realistically, it will make up 2% of their sales if they are lucky, but wheres the midrange? Right now, at £130 for a 260gtx, £150 for a 275gtx, they may be the fastest cards Nvidia have, but they are still midrange cards in this market.
So the reality is they aren't selling mid, or high end products anymore, and they only have a high end on the horizon for at best, another month away, at worst 3-4 months away. Their "mid range" version, will almost certainly not fall into the same price bracket as their current 260-285gtx cards either, meaning they could be 6 months away from a viable £100-180 card to sell, and thats the bulk of their profits in that section.
Unlike ATi who fairly quickly replace a range top to bottom, Nvidia have lagged on their mid/low end parts heavily from the high end for the past 2-3 generations. While they had the 280-260 range out from £200-400, they were still selling 9800's as their midrange, and still today, sell them as their lower midrange as a GTS250.
This is the problem, Nvidia, unlike ATi, haven't stopped producing their high end until months, and months after their new high end launches, just sell them as midrange cards.