the reason why psn is so slow is because of the pitiful amount of RAM in the ps3.
it's definitely not the cell CPU holding it back. so therefore with the new ps4 having 8GB of DDR5 I think the bottleneck will most likely be the CPU this time round as the RAM is simply something we have never used before for system use.
the only thing that is going to stop the ps4 from succeeding is price or a high failure rate.
the cheaper console tends to be bought by everyone (kids and adults) and the more expensive console by adults (due to price), kids are a much, much bigger market but they do not have as much disposable income if any and rely on their parents to purchase so they opt to buy the cheaper console.
if you had to ask me which was the better console, i would say the 360, but it's high failure rate destroyed it for me.
ps4 has fixed a lot of the problems the ps3 had, no headset input being a major one, cross game chat, better OS and store, etc, etc.
the only problems i can foresee therefore now are pricing, because sony have always made the better consoles with low failure rates. if they price it right to capture both ends of the market (kids and adults) they should overtake the "one" in sales, if it is priced too high and the "one" is cheaper, they are going to lose out on a lot of sales to kids.
people on here are going to say having less kids online is a good thing, but if it makes the console less successful, it is a bad thing, publishers and developers would be more willing to give exclusives to the console with more buyers.