One of the big hang-ups with MMO permadeath is that the player is the base unit of the game, not the character. Social organization and cooperation are the core or a lot of MMO gaming, so if I go on vacation, and come back to find that all my mates have died and been resurrected a dozen times and I'm the odd man out because I'm still specced for the team we ran two weeks ago, then I'll feel like my investment has lost its value.
Maybe you could simply remove the social aspect. There's a weird social experiment MMO, called
The Endless Forest where players are anonymous non-human animals populating a server with an interface that is limited to basic emotes and actions. You can give your little guy a sigil, some unique symbol that will allow others to keep track of individuals in a group, but it isn't a symbol that appears in any alphabet, and there's no way (last time I checked) of making any kind of a "buddy list" or keeping in touch with acquaintances. No guilds, no punk lists, no e-peen, the only thing that matters is what you're doing at that very moment. That game is a tranquil environment, where there's very little to accomplish, but the act of meeting people, interacting with people and then leaving them and forgetting them entirely is perhaps the social equivalent of a roguelike.
I just played a couple rounds of Starcraft II, and the matchmaking there resonates as well. I get chucked into a match against some random dude based on opaque criteria, we duke it out, I do a good job making SCVs but forget to keep up with viking production, I lose air superiority and his tanks faceroll me. End match. My stats are modified minutely in a way I can't really discern, and then I sign up for a new match. New opponent, new map, new chance. I harass with a probe, I expand, I mess up my micro and lose my immortals, then I just go balls-out on stalkers and colossus and win. End match.
No how about a game where you get to make a character, engage in a cooperative/adversarial contest and then resolve the session in one of three ways: You die, you retire or you "stable" the character for future use? It may or may not be set in a persistent world, but getting saddled with a random team based on matchmaking heuristics and then being called upon to play without any kind of direct communication (no voice, no chat line, at most maybe contextual utterances like you see in co-op Portal 2) would allow a player to immerse himself in the game and then emerge from it without a strong sense of loss if/when their character is destroyed or abandoned. You might add visible accolades and designations, like the insignias in Call of Duty, or you might black out all indications of who you are playing with and against. More or less complex challenges, different gear or options, all kinds of stuff could be "unlocked" on a per session basis, so a handful of experienced players might find themselves in a hopeless situation, on a decompressing spaceship full of angry aliens, and the episode resolves when one guy tells the others to get bent, shoots his buddy in the back and takes the only escape capsule to safety. Sweet.
A robust, versatile engine would be called for, and I think it would be totally acceptable for the vast majority of sessions to end in anticlimactic death for all parties. There's a Pen & Paper RPG called
All Flesh Must Be Eaten (which I've never played), where it seems that every game must inevitably end with the death of all player characters, and the fun is in authoring your own last stand. Maybe you get devoured in the first four minutes, cringing in a corner, and then go watch a movie and drink a beer while your buddies wrap up the round. Maybe you go down under a pile of undead, pulling the pin on your last grenade while your buddies escape into the sewer to fight a little longer. Maybe you get a call from your mom and shoot your brains out so you can go eat dinner. Maybe you're the last man standing, with an empty pistol and a bent machete, pushing that Sisyphean rock until the DM tells you that it's 4am and your character had an aneurysm from hyper-elevated badassitude and it's time to go home. Any way you look at it, you need to be able to shape the game and the game world to meet and defeat the players.
The bottom line is, an anonymous matchmaking session-based MMO roguelike would work if the player could sit down, fire it up, have a rewarding experience and then walk away. Being able to share a persistent experience with people can be undercut by player mortality. But by eliminating the persistence of the characters, permadeath can be convenient and fun. I swap Skyrim stories with co-workers, and we enjoy the shared experiences despite the total lack of multiplayer in that game. Same with Dwarf Fortress--I'll talk to a buddy for hours about the time his complex clockwork drawbridge system malfunctioned when a cat fell onto a pressure plate and squashed all his archers. Make a game that provides an endless parade of fun, engaging vignettes, and you'll please players again and again.
I'd recommend an aftergame lobby, where the dead can meet to talk about what happened, exchange insights and maybe even peek in on what's happening since they died. Just be careful not to introduce metagaming opportunities that will corrupt the formula.
