There's nothing flawed with my idea, you can pay 5$ a month extra for questing and once you get to level 90 you can drop the extra 5$ and pay for PVP or raiding only, or both
Want to level an alt? Start paying an extra 5$ again.
Games with cash shops offer these under forms of monthly/weekly passes. In TOR for example, in order to do more than 5 PVP matches a month as a non-subscribing player, you can either cough up 15$ and have access to ALL THE CONTENT, even if you're not using it, or you can pay like a few dollars and have access to more PVP matches that month and that's it. You don't have to pay for PVE content you don't do once you're at max level if you don't want to.
Seriously, it's not that hard to understand.
As for the guy who the thread was not directed to him, he just said that "I'm still playing" (ok, why do I care?) and "I wouldn't want this if I wasn't playing" (ok, why do I care?), since this thread is directed to people who left and are thinking of coming back.
Also I didn't understand what you were trying to say through all that math, like was there a point or a conclusion to all those random numbers?