you might want to get some FreiCoin if you like demurrage.
Demurrage is a great concept for traditional fiat-like currencies, but not a Bitcoin-style system: it attempts to ameliorate the issues inherent with human management. Since there is no human component directly involved in management of the money supply of Bitcoin, demurrage is redundant.
Eventually,
Triffin's dilemma overcomes demurrage anyway. The divergence between the need for a savings vehicle that is being eroded and the need for price stability which slides further out along a parabolic curve causes too much strain over time, and no amount of effort can prevent a collapse then.
Bitcoin technically solves the dilemma by allowing for theoretically unlimited decimal expansion of the unit, similar to going from ounces of gold to grams. Instead of forcing either perpetually inflation or adamantly static supply, Bitcoin allows for what is effectively an periodic, incremental inflation; these resets are somewhat jarring, but should be mediated so long as market forces can function freely.
Prices would be relatively stable within a range and yet the same unit of savings still exists and remains fully intact, the same as if gold were infinitely divisible and we were able to actually make use of it an atom at a time. Anyone who had a single ounce would be immensely wealthy if a single gold atom were used as a $1 bill is today.
Obviously we can't use individual gold atoms as money in any known practical manner. Likewise, the difficulty that arises with Bitcoin is getting a protocol change that allows for further decimal expansion to actually take hold. A potential solution may be an alternative system that acts as a counterpart by removing the block generation limit, allowing for indefinite expansion. That would work the same as gold and fiat today, only there would again be no direct human management of the unit supply.