Bear in mind I have not played Eq for over a year. Some of this may be way off base - or maybe they've already done it.
Were I Eq king for a Day I would:
(1) Implement huge rewards for doing various cool older quests the first time. E.g. you turn in your first gnoll fang (or set of 3 or whatever) and get a big faction hit, nice cash and very good exp and perhaps an item. Re-do it and get what you get currently.
(2) Implement a pause mission button on instanced content like LDoNs. Only usable when no mobs are within X distance of any party member. During the pause, everyone can talk to one another, sit/stand, do emotes and /dance commands, but no mana/hp regen (or, if that is too hard for them to code, mana/hp/end all return to the level they were at when the pause began). You could only pause once per real life hour and only for, say, up to 8 minuets. Some of us have real life stuff to do (smoke/bio/crisis/etc) and would like some sub-game area (not the top tier, high end stuff - so maybe not in "hard" LDoN missions or similar content) where we can live more normal lives. Only group leader could pause. People would just say "AFK five for XXX" or whatever and the group leader could simply choose.
(3) Develop "training" raid content. Likely instanced. Everyone who goes gets a NO DROP item which, in essence, is a sticker saying they attended raid training camp. I would have 3-5 "levels" of this training - some of which could be done at lower levels (e.g. 40-60ish but I might have some easy ones even lower as well...) and perhaps the top ones would be for 65+ with significant AA's. One great, unique, thing about Eq is the raiding. This would get people into raiding more easily. It would not be for uberloot but for the certification that these people know something about raiding. And thus the raids, particularly the latter ones, should be challenging. They should require strategy. Yes, even if you can look the strat up online, so what? That is similar to real raids.
(4) When you win a LDoN mission, groupleader should get a message asking if the group wants a special challenge. If they do, the whole dungeon clears and they get a single named mob (standard for that mission type/difficulty). If they beat it, they are asked if they want a harder challenge. Perhaps this would be a slightly harder named or a named + an add or something. I dunno. If they win they should also get a chest to try to open in addition to the usual loot. Perhaps since this is "automatic" loot (for winning mission) it could be NO DROP loot?
(5) I would forbid further "bait and switches" after expansions are released. I would announce that future expansions will be far more carefully beta tested and that we do not predict any major changes after release. People will know what I ment. (Obviously, SOE cannot admit their previous wrongdoing for legal reasons - even if legally they can do what they have done, they do not want to give opponents ammo). When beta is done and the expansion is issued publically, I would have it tuned so that I don't have to nerf it hugely within a week or two. Obviously, if there is some rare combo of AA's or item effects which turns out to be superpowerful it needs to be nuked. However, vast broad reductions in the loot and/or exp given out (a la Monster Missions and many expansions I was involved in) by the expansion would never happen on my watch.
(6) I would drop the subscription price to half what WoW charges: $7.50 per month, $6.50/month for six months at a time. And I would vastly reduce the cost to transfer characters between servers and change names.
(7) Not now, but sometime after Christmas when people are through playing with all their shiney new toys, I would email everyone who had left the game for over a year and offer a month of free playing time if they fill out a survey on the webpage. The survey would detail why they left, what (if any) other MMORPG's they've played in the interrum, and the positives and negatives about those. So as not to swamp the servers with returning people (if any come at all - I don't know) I would start small and gradually expand the program to include all people who had ever quit the game.
(8) I would find to allow people to not have to load the new character models and shorten the entire startup process.
I strongly feel following a program similar to this could return Eq to being the premier MMORPG and secure its future for a very long time.