I almost never play online and I've been paying for PS+ for about two years now. I find the value to be worth well over the subscription price and I would continue to subscribe even if it had nothing to do with playing online. That value is why PS+ membership was rising well before the PS4 was released.
As for paying for "online", it's going to be interesting to watch Nintendo's long-term strategy. Games keep getting bigger, which means the related costs for online games will continue to rise. Obviously, maintaining a high quality network means a hell of a lot more investment than when video-game consoles were just unconnected boxes. I'm sure Sony realized that the overhead from this will only continue to grow, thus leaving them with dwindling profit margins, as the consumer price for games has remained the same.
As I see it, Nintendo's possible routes are, A) build a high-quality network with free access and eat the rising overhead costs themselves, B) build a high-quality network and charge extra in some shape or form, 3) continue forward with a bare-bones network while attempting to de-emphasis online play. The last one seems to be their chosen path but I'm not sure it's going to meet the needs of the future all that well.
