An autarch isn't an exarch as far as I know. I'm not sure the path of command even has such a thing, though it ought to. I suppose the niggle here is the cost of achieving the rank of Exarch. If becoming an Exarch for a player was just one step along a road of trying different things then you're right. If becoming an Exarch of a favourite Aspect is the crowning glory of a character's path, it's a different matter. So, if you make it clear to the player how important a decision ascending to the rank of Exarch is for the character, then frankly I can't help but really like the idea of this permanence.
While Autarchs aren't Exarchs I'm not sure if they can leave the Path of Command. After checking my codex it's implied Autarchs are the Exarchs of the Path of Command. Yeah but I still think you need some way to change classes perhaps the next time you die you "leave" the armour and somebody who does want to be an Exarch picks it up and replaces you leaving you free to change classes. I think to make it work as a game Exarchs should be a elite within squads rather than sergeants and a person is still elected to be sergeant who can then progress to higher ranks.
Intriguing notion. The 'Path of' books made it seem like an Exarch leads a squad from each shrine but in table-top you don't need an Exarch at all, you bring them for combat ability not for leadership. Most of the time a squad of 'grunt' aspects did the job. Fluff wise it would be fine as well since an Exarch excels at the martial discipline the shrine embodies, leadership isn't a mandatory part of it. I would be fine with your suggestion.
As far as other games are concerned, SWTOR technically 'locks' you into a choice you make early in a characters career, but there is flexibility within those constraints. The original idea COULD work, but it would just be easier on everyone (devs included) if we all simply became Autarchs.
As long as there is a fair warning, and the appropriate bonuses attached to it, then yes. I think it would be for the best if we had Exarchs. Of course, having the suit of armour pass from one Exarch to another and having their minds become a single entity might be a bit more difficult to pull of, but that I can live without.
I see where you are coming from, but on balance I'd have to say no they are different, but yes it comes to the same thing in terms of an Autarch always being an Autarch just as an Exarch will always be an Exarch. First up, while I'm pretty sure that the term Exarch is specific to the Aspect paths, I'm guessing you mean it as any Eldar that has become obsessed with a path and cannot leave it. The path of command is related to the aspects of Khaine, but they are essentially different and unlike the Aspects the Path of Command is a lifetime's commitment to serve the Craftworld. An Autarch isn't lost on the path of command, but is chained to it by ties of duty and honor. So yes the Autarch will most likely always be an Autarch as it is a total commitment, but this is a voluntary thing to do with a higher calling rather than a failure in their ability to keep the core of themselves separate. The biggest difference between the two is in how the other Eldar react to them... Exarchs are treated with honor, but always with distrust, fear and a touch of disgust.. They are examples both of the heights an Eldar can attain, but also the depths. On the other hand Autarchs are nearly always universally respected as protectors and paragons, particularly since they have shown the willpower to walk the many warrior paths without falling to their temptations.
90% times 40k games are separate dimensions where some random dude takes the place of Cato Sicarius and BLUD RAHVENZ lose thousands upon thousands marines. And steal themselves all the goodies other chapters never dreamt of. yeah, we'll have literally thousands Ultramarines. Fluuuuuff raage! So you mean that in a day's time a chapter can lose thousands of space marines and instantly replenish their numbers? Only if it's all prognostication.
The thing is that it can't be prognostication because the world acts exactly as though all the events were happening in the normal sequential order and completely ignores these 'supposed' changes. That aside it's a really, really bad way of fixing the problems as it basically makes the entire game meaningless not to mention raising countless paradoxes. I know you won't like hearing that and I feel a bit of a heel for even saying it, but it's kinda true. Logical issues notwithstanding every Marine or Ork player would effectively be told that their only role in the game was for the arch manipulator (chaos or eldar) who was carrying out this foretelling to find ways of defeating... You're basically relegating 50% plus of the playerbase to the position of 'virtual' disposable stand in for bad guys!... Yeah that's not going to annoy the hell out of them! But the huge glaring issue of how to get other people to join in with this eldar/chaos ego trip aside the population churn 'problem' is only really an issue if you outright state that the character is dead... hell they could just be hospitalized - problem solved! - an unstated percent of the characters that fall in battle are not dead, just badly injured. It's really that easy.
The prognosticars can see any and all variations. Why not? I won't mention some Space Marine failures that have no conenction to 40k Universe at all. Meningless separate dimension. I know you won't like hearing that and I feel a bit of a heel for even saying it, but it's kinda true. The God_emperor of Mankind looks at you with disdain and slight misunderstanding, for He does his best to find the way to bring Humanity to the front and bring forth the end of days for chaos scum and Xeno menace. Yeah, but hardly there's anything left to Hospitalize after a CHAINFISTING or LASCANNON IN DA FACE All factions are divided into "disposeable as hell" and SPACE AMRINES THAT ALWAYS fight enemy completely unsuited for killing their roster...
