If you read the thread, you'd see that I posted a two-sentence "proof" (<-- I used the scare quotes to indicate that it probably wasn't a proof), and then asked people to poke holes in it. 

I agree with @molecular.  The economic pressure can also be relieved, for example, by people voluntarily leaving the economic system.  This would drop the supply curve such that it meets the demand curve at a point near the quota (Qmax).

What is interesting, is that either way (by fork or by people leaving the system), somehow the result is that Q* ends up to the left of Qmax!  If this simple result is true, it would imply that it is not possible to use a block size limit to drive up fees.