Well, that's the theory, at least!
My plan has been through so many changes (I have never "changed plans", but the original "Code Monster" plan has changed repeatedly) that it hasn't really worked out that way so far. In fact, my quota as shown in the panel has actually decreased, and is now just about the same as as a new "Happy Hosting" plan user's. I'm thinking my quota number just got so ridiculous the system gagged on it (thought it was an error?)
I suspect if I complained about this they would "adjust" it back to some even higher outrageous amount, but in reality there is just no need to do so. Sure it might be reassuring to see a an ever bigger number there, but the point is that I have more than enough to meet my needs. And, if they do what they have indicated and double that amount for existing users, I'll have "more than double enough to meet my needs".
My thinking is, "I'll worry about it when/if I start to feel cramped ... if I live that long."