I think that if this game reaches its maximum would potentially reach the population to maintain two lively servers with all the continents / naval combat etc.
I think anything more than that would require a resurgence of interest in the entire MMO genre.
Realistically I think more than one server will feel pretty dead.
MO1 felt somewhat lively with 200 average players (Not even joking.) Was it super healthy? Of course not, I wont even dare argue that. But it felt 'okay' around 200-400.
If the world is 6 times larger, then we can make an estimation of something like this...
200 times 6 is 1200.
400 times 6 is 2400.
Now for anyone who has played in MO1, those numbers are I N S A N E for 'amount of players'.
We already have a rough idea of players that purchased into alpha and or played it. It's easily 1000 plus and if what Henrik said is true, it was what.. 2k+ at one time with 5k in total trying it out?
Let's be generous and we'll divide that in half. That's 2.5k. That more than meets the healthy requirement, by my own standards of playing MO1, for a good population.
You don't need as many people as you actually think to have a 'healthy' population on MO2. I honestly think 2.5k players would be crowded, that's an awesome number.
This is only from the alpha / beta. Could you imagine a finished product, and on Steam + marketing through YouTube, Twitter, etc.
Henrik said himself the players are the best advertisers. Easier to advertise a game to friends when you don't need to mention they'll have 100+ ping always, also easier when the game is in a good place with all things that it needs.
I'm open to my argument having holes poked into it, because it isn't concrete; I'm aware. But I don't think two servers would kill the population. Especially if you could play on both with two individual characters or one single character that only shares skills and not material items.