It is just an idea. Not final at all. Just to keep that in mind while designing the whole system.
Constant rate increase looks good until 1 say satoshi reached. Or maybe 10. But later it possible create problems with the exchange with constant increase of "reserve" for future conversions up to enormous amount. It greatly depends on unpredictable conversion demand changing over time.

We need to keep this obvious flaw of this proposal in mind. I can't  even imagine what distribution law applicable to that conversion-rate scheme. Completelly no idea ATM. It prevents me from predicting any demand in conversion with the reasonable rate change approach. Linear 20% a week increase is just for illustrative purpose - no rational behind this figure.