Won’t happen period Matt peddleston himself has stated in numerous live streams it’s complex not realistic and would be heavily abused by griefers like in gta online it’s best kept solo
Unfortunately the game is already poorly optimized without multiplayer so including that would just absolutely plummet the game.
We need multiplayer? Don't think so, if you personally need multiplayer, then there's SimRail for that. Why isn't it coming? If you've taken a glance at the state of the game now, multiplayer is going to be a whole other development nightmare.
SimRail or Run 8 as I expounded on in the previous thread about MP which appeared just a couple of days ago. Did we need another one so soon, paticularly as the OP doesn't even expand on how it might work or what benefits it might bring. Well in the case of SimRail, it's sounding a mutual horn on the off chance you pass one of your buddies. In Run 8 there are no buddies, just a bunch of grizzled curmudgeons who resent you joining in the chat and delete your train if you decide to go off and return later.