Eventually that little line on your graph will level out. Once all BTC are mined and in the hands of bearers, inflation will be impossible because the amount of BTC is FINITE!
True, but since that is approximately 127 years away, can we assume that the bitcoin supply will be inflationary for the entire lifetime of anyone alive today?
I suppose it depends on whether you count "lost coins" as a reduction in supply against the generation of new coins, and how high the rate of lost coins is in any given year.
No, we can assume Bitcoin is not inflationary at all but has a constant of 21M BTC outstanding. That some of the Bitcoins haven't been given out yet is irrelevant.