Those ideas are a good start, but there are a few things worth noting.

D&D has an initiative system to let players know who goes first during combat. There are entire builds and game mechanics designed around initiative, so it seems like a bad idea to create a specific format where players work within threads to come up with their actions. Plus, the DM needs to know when it is the NPC/monsters' turns to act, and it doesn't work correctly if the players are each making numerous threads for their actions.

A better way to do it is to hold players strictly to their initiative rolls. A new thread would be started for the initiative round, but the game cannot (and should not) continue until the player whose turn it is makes a move.

Yeah, this could take hours to wait for your turn to play, but to be honest that's going to happen anyway. There's no way around that in text-based roleplaying. Really, the only way to avoid it is to make agreed-upon meetup times for sessions, but it didn't sound like that's what you all were trying to do with this sub. Plus, there are much easier ways to play the game like that than on reddit.

All that aside, gameplay outside of combat will be easier to manage. There isn't really a turn-based format for roleplaying non-combat encounters in D&D, so it'll be just like a giant thread that the DM monitors and chimes in to speak for NPCs.

The best way to keep up with chronology is for DMs to start new parent comments with a time stamp and some exposition (any DM who has done text-based roleplaying before would know how to do this). It would look like this:

Example of a new thread:

3 o' clock in the afternoon. The Orc King's Layer. You enter a thirty-square- foot chamber with torches on the walls and chains and iron cages hanging from the vaulted ceiling. On a platform near the north wall you see King Grunk sitting on a throne of bone. Three orc shamans stand before him, waving their hands over their heads in a mystical manner. King Grunt drinks from a cup of some strange red liquid, then screams some gutteral words at you. All players...roll for initiative.

All the comments in that thread would then post their initiative rolls, and the DM would ask each player in turn for actions.

Upvotes and downvotes are fine and dandy, but players would definitely need to sort comments by time and keep close attention to the initiative order.

Any piggyback suggestions?