V2 means that, right now, there are two seats available for segment upgrades. It doesn't mean 2 total.
Whether someone has requested an upgrade is not relevant. V2 will not drop to V1 until one upgrade request is actually processed.
In any event, it's pretty useless, because Delta will usually add more V seats as departure time approaches. Let's say there are a total of 7 available seats in First Class (i.e., seat map = actual bookings, which is not always true). Eventually, the V bucket will go up from 2 to 7 (unless someone buys A or F), and the next 7 people on the upgrade list will be accomodated. This might be tomorrow or it might be 35 minutes before departure.
As departure date/time approaches, Delta might also add inventory to the G bucket, as well as R, N, and in fact just about any booking class.
One thing to keep in mind when looking at booking class availability is that it has almost nothing to do with the number of open seats. Inventory management can add or remove seats as they see fit, so consider the inventory numbers to be quite temporary in nature.
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"Don't be sorry. Be quiet!" -- Minister, Spaceballs
[This message has been edited by JS (edited Feb 10, 2004).]