Back in Age of Conan, when they introduced the Alternate Advancement system which is similar to ESO' Champion System, you could gain points either by grinding XP and/or investing time in a skill..
The alternate advancement System offered an over-time mechanic, available online or offline. This is a straight conversion of points-to-time. A player will be able to select the Perk or Feat he wants to train, and as the clock ticks away AA points will trickle in to that Perk or Feat. The gain of course will be far less than what one would get by actively playing the content which generates points. This is intended to reward subscribers but also casual gamers.
So instead of AA points like in Age of Conan, make it so every 24 hours (whether you are online or offline) you gain let's say 1 CP.. The numbers can be tweaked..
Please do consider this system, a win-win situation for all: it will immensely help casual players while keeping the hardcore gamers content.
What do you guys think?