The example of the Mega-Adventure should illustrate, if anything, why it is a *bad* idea to try to choreograph a major world-shaping development. (Actually, more than that, it's an example of why it's a bad idea to let too much responsibility fall into the hands of one person. If Rystil had stayed to finish what he started, it might be looking like a great idea. But the fact remains that, when it was flourishing, LEW was organic, developing through lots of people's small inputs and no efforts at global-scale plot lines.)
So I think this is a bad idea.
Moreover, you seem to think that the failure of the various shard quests ensured the lichwyrm's victory. How so? One set of quests to secure the shards failed. That means that the shards have not been secured, leaving them... exactly where they were before. There is reason to believe that this little-known cult poses a threat of *possibly* immense but really uncertain severity on a time-scale that is completely undetermined. So, there's a story point that we can work with if someone wants to. There's the key. If someone wants to. If any prospective DM has an idea for an adventure revolving around the cult of Vildaxaranthus showing up in <fill in your favourite ENworld locale>, I'd love to consider it. If not, then the cult continues to be secret, of unknown scale (or possbly even apocryphal, as Trouvere suggested).
Myself, my sense of investment in this project called LEW is mostly tied up in the story of Nurlan the minstrel in denial of being an adventurer. It's a storyline I've started, and it's one I want to play out. More than anything, what LEW offers to me, is the opportunity to play this character I've come to love. Everything else I do -- as a judge, a character judge, an occasional DM -- is my way of giving back to the project that I've enjoyed so much. Take away the opportunity to play out his life story, and you've lost my interest.
There is really one reason LEW is flagging so much: a shortage of DMs. I'm a judge, and I can't remember how long it's been since I've seen an adventure proposal. Unless you can convince me that our shortage of DMs is due to the current state of the world, and that a different one would inspire more adventure ideas, I fail to see how your proposal would help, and I can easily see how it would hurt, by destroying the continuity that hooks existing players in.