It seems to me that reducing supply at an aggressive rate and then steady would motivate circulation of coins, and probably give a nice steady rise to them. This would work well for coins that are actually useful and used.
Thoughts?
See, if the coins are actually useful and used, then you don't need to include demurrage to motivate people to use them. It seems like an easy system to game too. Can't you just periodically move your coins to a new address to avoid the demurrage fee? So we have all these transactions going on but that doesn't translate into real use.
Coin hoarders are always going to exist as long as speculation plays a factor. Until it gets to the point of seriously harming liquidity, I don't even necessarily see that as a bad thing. Fact of the matter is though, most of these coins are only good for hoarding and trading. Give these coins real world uses if you want to see them used more often.
And I don't agree with the statement "The problem with a lot of altcoins is the large supply" if you mean it in the sense like, "OMG, there are 20 billion coins?!?!?! Too much!". I never understood people who think like that. It's all just moving a decimal point around. A billion coins or 1 coin, it's all the same to me. Market cap is all that matters.
Now if you mean "The problem with a lot of altcoins is the large supply" as in the problem with altcoins in general being that there are a theoretically infinite number of altcoins that can be created and a limited number of BTC, so in the grand scheme of things all alts trend toward 0, I agree that is a problem. We can fix that by not supporting scams, shitcoins, and clone coins but that is an increasingly difficult minefield to maneuver these days.