Yeah I know.. I was thinking the main concern people seem to be having is that they'll be able to max out a character before the game is over. Even if your maths are right on the money, people (obviously) have a hard time believing that it will take that much time. Simply showing that even if they used past leveling systems or even something doubling past leveling systems still wouldn't get them to that maxed out character could alleviate that concern... (or maybe it'd make the concern worse because lots of people like to max out a character.)
At any rate, I'm sticking to your leveling theory because I like it best. I want that 2,500 hour max character challenge that I'll never actually complete because I'm lazy.