They already have a subscription-based online-service, and I doubt they have any good reason to change it.
The main (and only for a lot of ppl) reason people pay for Xbox Box, is to play online.
Xbox Live is the biggest cash cow Microsoft has, It's pure profit, because they could pay the costs of running the service with ad money alone.
Sony (like every other comany...) is a company with the main goal of making loads of money.
And as you all know, Sony as a wholle has been having a lof of problems lately, so...
It all pretty obvious to me, it sucks, but i really believe there is no chance they will leave that money on the table.
people are sick and tired of paying for something they think, and rightfully so deserves to have for free, and even though they pay for something they still get insulted by getting ads thrown in there face
as far as i know, and with a quick google search to back me up, sony will not say how many psn users have ps+ but it is estimated that a minimum of 13mil users have one, thats how they make the money instead of forcing it out people.
well they are doing fairly well, since its the most popular console in both europe and asia, basically they only loose to xbox in america.
granted they have a good amount of problems when they launched due to the fact that it was harder do develope for then xbox, and the fact that it was way more expensive but that kinda also had something to do with the fact that it had a blu-ray player in it. the ps vita is not doing great how ever but thats not what we are talking about.
i would actually be surprised if they do
and it would not surprise me if ms also stops charging money on the next console and try to mimic sony in some form or another
but the last one is more speculations on my part