After speaking to quite a few ps4 players and visiting forums seems that not many are willing to sub to the game.
Me on the other had will definitely sub but if there is a small population it doesn't make for a good experience.
So if this happens could they not merge the pc and ps4 server?

doubt it. thats a big can of worms

There aren't too many big name fantasy rpg games on consoles yet so the field is wide open. If the game is good, people will sub. If it isn't, they won't.

FF ARR have manged to pit pc and ps3/ps4 together I know it's a different game with different mechanics but it works fine and keeps the population up

PS4 will have its own beta. You'll probably get a better idea then. Quality games on the new consoles are pretty slim now, so it should be good anyway.

True but the feeling out there at the moment isn't looking good. I know I can't possibly be speaking for everyone but im just generalising from the people to whom I have spoken to

What do you mean by "sub" the game?

I mean commit to a subscription for the game

Considering that there is a limited amount (5.8 million) of PS4's in circulation right now and the negative feedback around paying to play the game on consoles, the numbers won't compare to the PC market.

Playstation execs said that they should be able to meet supply by April though so who knows how that could impact sales. Zenimax has pretty much sold this game to the MMO/PC market, judging by the all the fanatics we encounter here on a daily basis, but i'm really interested to see how they're going to sell this game to the console players who in theory, make up for a large share in video game demographics.

Very true and out of consoles sold their not going to get a 100% sale rate so population needs a bit of looking at. I could be wrong but I don't think maths lie.