lol pre-orders running slow? How are you concluding this.
It seems pre-orders at gamestops are just getting reallocated. Sony is just in the beginning stages of shipping components for manufacturing consoles, and they have 5 months to get the allocation for pre-orders right. They have adjusted their forecast already, and any details we have now can't give us any clue what will happen in fall.
These retailers were just taking pre-orders with a low estimate on how many consoles they would get. Gamestop corporate would tell each store how many. Sony gave them the okay to take on more pre-orders, means that Sony plans to make enough consoles for them.
In terms of surplus, I'm sure Sony would rather have 6 million units shipped and 5.5 million sold, than have 5 million ship and only 5 million sold. As many people out there that want a PS4 over X1, there are some that are also going to get both. And if they were planning to get PS4 first and it's sold out they may just switch and just get X1 first. Either way I highly doubt they will have a massive surplus of units out there. And Gamestop won't be the place to find it, since it seems each store is only gonna get the units that they have preorders for. For buying on release day w/o preorder you would be best off trying Walmart or Best Buy, and even then good luck.