Thirdly... So what if there are more hard forks later? The current proposal from Gavin also guarantees that there will be more hard forks. The proposal is a guess at what might be needed, it does not measure the block chain in any way to determine how to set the right block size. It is a good guess, but it is just a guess, same as the 1MB limit was. We don't finish with hard forks by going with the current proposal either. So none of your argument here makes any sense at all.
The maximum maximum block size will become 16 GB on Jan 1 2035 with Gavins proposal.
So I guess that means that another hard fork is not needed until 2035?
If the population of Earth in 2035 is ~8 billion, that's 2 bytes per block, per person.
Given 144 blocks a day, that's 288 bytes per person, per day. If everybody uses the block chain twice a week or so, the block size proposed for 2035 should be adequate.
Since most people don't do money orders, remittances, or savings-account transactions that often, honestly I think that ought to suffice for "ordinary" use by ordinary people, even with a very high rate of adoption. I mean, some will be using it for every cuppa coffee, and some won't be using it at all, but it averages out at what I'd think of as a normal rate of usage for complete mainstream adoption.
Rather than extrapolate on what might happen, a better question to ask yourself would be: "Would there be any negative effect if things are different from this result?"
Bitcoin is not improved by making it work. It already does that. Bitcoin is improved by making it not fail. This must be the goal of the fork.
Consider if there is growth and shrinkage in either bitcoin use or populations? Even a miner with a smallish percentage of the hash rate could significantly raise the costs for everyone else.
Bitcoin is as excellent as it is not so much because of what it can do, but also because of that you can not do.
Adopting an inaccurate
and indefinite exponential growth proposal based on extrapolations is folly and hubris. It introduces new failure modes. It just isn't worth it.