This side-ways reality was just the place in which one goes after death, before they are able to move on. This place could last 10, 100, or even 1,000,000 years. But for the viewer, that might be hard to understand because in that place, there is no time – no “here and now” as Jack’s dad says. Being so used to a schedule and time as we are, it’s hard to fathom that time does not exist, and that what we were seeing of as ‘time’ in this “flash-sideways alt-reality” was not as we know time.
For example, the line “some died before you, some long after” tells us that even though most of our main characters have met back up with each other around the same time in this flash-sideways, some have been in this place long before others. The dialogue between Hurley and Ben outside the church prove this, when Hurley says to Ben, “You were a great number 2″, in which Ben replies, “And you were a great number 1.” Meaning, Hurley and Ben went on to protect the island, maybe even for a thousand years, before someone replaced Hurley and Ben just as they replaced Jacob and Richard.