HoT Beta Portals
Yes. They will fill out the ranks with invites to newsletter subscribers, the same method used to get all the beta stress testers for the first round.
Also, they flag accounts, not the number of portal drops. One person getting 2+ stones does not take a spot from another player.
they already upped the drop chance after the 1st week, and it is not a matter of there being a specific amount of portals that can drop, but rather how long ANet let the game generate portals by means of RNG. and yes as Donari said they will also fill in the gaps if they dont get enough in time with newsletter subs