After a week, my further thoughts:
The Mega-Adventure is the elephant in the room. I have been reluctant to comment on it previously because none of my characters is involved, but I stayed out mostly because I had misgivings about putting all the eggs in one DM-basket, even considering Rystil's astonishing average of 35 posts per day when it began.
Putting so many characters "in synch" - all heading off to adventure simultaneously - was by itself harmful to the health of LEW as a living world, I believe, beyond just shutting out other potential DMs (thegreyman suffered here, I think). I realise people prefer earning XP in an adventure to hanging out in the Tavern RPing, but when I started out here, I liked the continual coming and going of various adventuring parties at the RDI, with the opportunity for characters to get to know one another, boast of their deeds, and form new parties. The months of the utterly silent empty RDI were depressing.
Howsoever, the M-A has collapsed. Many of the judges have expressed the intention of reducing their LEW involvement, so they are unlikely to want to complete the adventures. In any case, these were supposed to be only the first round, followed up by yet more and then some kind of grand finale. Does anyone really want to set aside the next year or two to run someone else's idea? Unfortunately, there doesn't seem to be a plausible way to resolve the storyline after the Council at which so many NPCs insisted they were certain of the danger. Oh well.
Regarding L4W: I certainly don't begrudge it its success and I don't think L4W per se is responsible for LEW's problems. I can't think of anyone who's abandoned LEW for L4W, though there are people who've left LEW because of 4e, of course. So far there's little overlap of players between the two worlds and those that are involved in both (covaithe, Halford, Phoenix8008, for example) are among the currently most active LEW members. Most of the new L4W players probably wouldn't have decided to participate in PbP without the push of the new edition in any case. That situation isn't going to improve. LEW probably has seen most of the players it's ever going to have.
Which brings up another point. If we have few new arrivals, there's a hard limit set to LEW's lifetime, as the existing characters draw nearer to 20th level. While that might take another 5 years for some, 10 years for others, eventually we'll all reach it. Long before that, the character of Enworld will be altered. Right now, we have no more than half a dozen active 1st level characters!
It's probably time to reopen the discussion on allowing a fourth character to those who want one. Last time, the idea was received fairly favourably, then the suggestion to allow additional characters only by spending DM credits was made, whereupon (perpetual danger in a forum for people who by definition are very fond of complicated rulesets!) the thread was diverted into the minutiae of a purchasing system, and foundered. Anyway, the situation has surely altered since then - of currently active players, about half have 3 characters already; the other half have had the option to post another for a long time but never exercised it.
Still, no matter how many characters there are available, we still need DMs too. I do intend to run something (for low level characters). All that really holds me back is the lack of available players (in a M-A Catch 22) and limited patience for making adequate maps.
The most important thing, I think, when it comes to running adventures is… to set aside ambition. I get the impression from opening DM comments of past games that there's a tendency to underestimate the length of time a game will take by about a factor of 5. Seriously. Timezone limitations, general life issues, misunderstandings, postings out of initiative order that need revising later (my personal bugbear), they all add up. Games that go beyond 18 months tend to die. It's far better to run a short vignette that finishes than to attempt some great masterpiece that loses half its players halfway through and then just peters out. If a DM wants to run something bigger, it should be chopped up into completable stand alone short segments, each ending with XP, level up and Orussus-based downtime for party members to be swapped out.
Well, that was disconnected and rambling.