I want to play through the main quest before I comment too much, I've read UESP but that's hardly a replacement for in-game lore.

Regardless, I'm not seeing much talk about this and it concerns me.

In particular, what does it mean to kill Alduin? Alduin is the aspect of Akatosh that is supposed to end the current "cycle" or kalpa, right? But Alduin got greedy and wanted to end the kalpa early. So the Last Dragonborn had to put him down.

But, what now? What will happen to the kalpa? Who will "restart" the cycle, with Alduin missing? I understand that viewing the Dragonborn as an enantiopmorph is controversial, but someone needs to destroy the world in order for the next kalpa to come about...Who better for that than the LDB, who defeated Alduin?

At a aminimum, the destruction of the agent meant to bring about the next kalpa seems like it should result in a Dragon Break. An avatar/aspect/bitty piece of Akatosh was destroyed. Why does this seem to be treated as insignificant? And how does the future of this kalpa look with the World-Eater dead?

Alduin played an essential role, right? He just abused his powers and was therefore not able to perform his important role. So who performs that role now?

My own hypothesis is that Lorkhan isn't particularly gonna let the kalpa end before his last incarnation achieves Amaranth, If not he would return to square one. Landfall will end up happening if the kalpa keeps running, however. Akatosh, who is basically a Time Dragon turned Space Serpent, sent the Last Dragonborn to stop his mirror brother Alduin.

Keep in mind that Alduin wasn't destroyed, the Last Dragonborn only destroyed his physical body, while his soul was snatched away by Aka.