I think it would be interesting if someone tried a fork of bitcoin with the same speed-of-generating-new-bitcoins-graph, but with no cap at 21 million btc. Instead, when the 21 million is reached, there will be an inflation of 0.7 % per year. That would mean that the money supply would double once every 100 years. That is an acceptable loss from a currency user's perspective, and would add any benefit(s) an inflationary currency arguably has. I could totally live with my savings halving in value once every 100 years, if that sacrifice boosts the usage of the currency, prevents hoarding etc.
Very cool idea!
We can all be early adopters of our own currencies! Seriously though, if A LOT of new chains were to start with the variables tweaked a bit wouldn't that just make Bitcoin stronger? You would have hundreds of tiny ones but only one big one. It would be hard for any of the small ones to really steal the market as they would be competing with so many others. Bitcoin has the advantage of being way ahead of the rest.