I don't really take that to mean anything specific to those games. That, to me, sounds like "I'm going to state the party line because it's not up to me what publishers choose."
Mostly because of the context. That was a question specifically about MMO games, and his response was that online multiplayer requires Plus unless a publisher chooses otherwise.
He's saying that it's up to the publisher who fronts the bill for those services. They can either work with Sony, who will get a cut, or require their players cough up themselves. Given that they're putting a big investment into the PS4, though, I would be shocked if many companies let their MMOs fall behind pay walls. I can't imagine it would be a huge price (afterall, Sony stands to win by getting more people gaming on the machine, regardless). But a purely MMO title is going to put a lot of stress on their systems, a la CoD, and they need to finance that infrastructure.
I can't imagine that there isn't already a decisive answer to this question. Yoshida is just taking the smart route and not giving an answer to a question that's contingent on decisions made outside of his corporation (as it's really up to them to announce them, and they have the option to decide). The two he named are already on the PS3, so I imagine their contract is more-or-less unchanged.
If they WON'T be behind paywalls, as of now, then Yoshida definitely doesn't want to have to eat his words if they change their minds later. He also doesn't want to be seen as establishing a precedent.
If they WILL be behind paywalls, as of now, then Yoshida definitely doesn't want to have publishers pissed at him for announcing that without approval, and damaging the hype for their games, and doesn't want to damage the hype for the PS4.
I doubt Sony has a preference, in general. It's going to come down to how the populations for the individual games work, and they'll likely review it case-by-case to see how much they can justify charging a publisher. If the majority of a gaming population already has plus, they'll likely up the charge to the publisher. That way, the publisher says no, and they get more plus subs, or they say yes and they charge more.
If most of them don't have plus, it behooves the publisher to agree to pay for multiplayer, which gives Sony a more reliable revenue stream than plus would have been. In this case, Sony probably would have lost money - the chances of such a significant group going for plus, if they didn't already have it, is slim.
One last thing: It's worth noting that publishers can do other things to make Plus a better investment. Maybe they negotiate to only pay for players without Plus. Well, if they add Plus incentives in-game, Sony wins by getting more subs, the publisher wins by not paying for the multiplayer, and the player wins by getting something in return.
So, at the end of the day, I wouldn't take this to be good or bad. Because it just sounds to me like a smart businessman making the smart business move and shutting his mouth on issues that are undecided, out of his control, or otherwise. All this says is that Sony doesn't have a MMO-specific policy in place that completely removes the Plus barrier. For all we know, a pure-multiplayer game will have heavily reduced demands on publishers compared to something like Assassin's Creed or Mass Effect, where multiplayer is a fun side-activity.
It'll be close, but Romney has the momentum.