S-curve emmission is in my opinion only possible with a central institution (call this a weakness or a strength of a social contract in cryptocurrencies)
it can be achieved without central instutution... Hard coded limits can be programmed.
For example: the high emission rate will only start when the hashrate crossed a certain point. It's all possible to programm
But this has nothing to do anymore with the XMR speculation, so let's stop this discussion here