Siegetank, I honestly don't think that's feasible.
Look at this:
https://assets-cdn.soe.com/uploads/dcsclient/000/000/052/321.jpg?v=0.0
That says there are 1557 zones in the game. To get 1 group in each zone would take close to 10,000 people per server. I honestly would be surprised if there are more than 30,000 people playing EQ right now. Of course they don't release numbers so it could be 300,000 but I don't get that feeling.
1557 zones includes instances and I'm not saying they need a group in each and every zone! Here, for example, is one suggestion. It's not all mine since I read something like this on allakhazam but I'm spinning off from that guy's idea:
Introduce quests, or missions, which require a lower level group of ALL players (no mercs, no boxes, etc.) and the reward is a top-notch High-level item, not tradeable but flagged heirloom, so you can move it to your high-level main on the same account.
So, for example, a 3200 HEM piece of gear which is a potential reward for a level 50 mission in Grieg's End, or 40 in Permafrost, or 30 in Kaesora, or 20 in Unrest or 12 in Crushbone, etc. The low level toon loots it but then can transfer it to his level 95-100 main. Sony devs have traditionally always tried to make high-end gear raid-dependent, or incredibly difficult or rare to obtain via group effort, and they could maintain the challenge just by requiring the group here to tackle a very difficult higher-level mob in the zone.
They already have built in code analogous to this in how they handle raids on Lady Vox where any player above level 52 gets banished the moment they engage. If the missions were instanced they could simply deny entrance to any player above appropriate level. None of this would be new or particularly hard to implement.
Unlikely to happen, alas but nice to think about it, hehe.