By "unprotected inflation" I mean the extent to which SP's share of the total supply is diluted by new supply. So if >90% is locked up the SP holders experience inflation with respect to their share of the total. If <90% is locked up, the SP gain what is effectively "interest" as you said earlier.

The maximum inflationary dilution that SP holders can experience (if >99% locked up) is about 10%.

All this talk of inflation distracts from the main point you made in your post which is that the total value can certainly increase dramatically. I don't really have an opinion on how likely that is. I will say that valuation of blockchain-based system is somewhat different from a centralized web-based system, even if the two do the same thing, since the latter derives largely from advertising (or in some cases direct revenue) and the former does not.