The only way SE can guarantee a 500k player base from day one is if they completely transfer characters from FFXI to FFXIV, if they want to start fresh a lot of people might want to stay in FFXI and FFXIV would need to establish its own playerbase. And, sincerely, from a business standpoint, allowing character transfers is the easiest way out. Besides, FFXIV level cap won't be level 75. And, who is to say FFXIV will have levels at all?
We should simply be able to transfer over our characters, stripped down to naked, if need be, that way we can keep our online selves (if you want a totally new character, or change some things like hair, etc, you could also do it, of course.
But, if SE decides to give me the option of having the same character (levels and all I will **** do it, ok?)
From a business standpoint, allowing people to start the game at 75 instead of spending all the time grinding through the levels is a horrible idea. Under no circumstances would SE be stupid enough to miss out on all the months that need to be spent levelling up a character.
It is also a bad idea from a game point of view as we all know what happens when you get someone buy a character at 75 - you get a really poor, clueless player with a high level character and no idea how to play the game.
And we don't even know if FFXI characters will even be compatible with FFXIV. We don't know how the skill-ups will work or if they will be exactly the same ones for example. There is simply no way that characters will be able to transfer over levelled in any way.
As for transferring over characters naked, reduced to level 1, we don't even know if the races are the same and they will certainly have different character models if they are. The Galkas don't even have the same body parts (if they are Galkas).
So if you have a decked out level 75 Galka in FFXI, complete with a basic PS2 character model and tail and it gets transferred over to FFXIV as a naked level 1 character with a PS3 makeover and different body parts, I don't really see how that is 'transferring over'. It's a completely new character.
All that's the same is the name which is basically the same as signing up to a new game with the same name.