This is only for new members.

Incorrect. You should reread what you included.

as long as your subscription remains active, we will continue to honour the same price you’re paying now as part of our “Grandfather Rate”

So you’re locked in basically to that rate until you cancel. But there’s not always going to be content that you enjoy playing. People who stay subscribed to an MMO forever are people who have tons of money to just throw away. I play World of Warcraft, and I have never just subscribed for a year at a time. Sometimes I get busy and I don’t have time to play, or there’s nothing I enjoy in the current patch.