This part I can't get my head around. If a 'currency' is a measure of an actual asset (swerving the money as debt issue) rather than the asset itself (meaning that you don't include money as part of 'all that has value' but rather, a proxy of something that has value), then it would surely mean that comparing satoshi to USD would become meaningless since it would have become its replacement, but comparing it to a house would still stand. After all, aren't we valuing houses with USD right now? It's just the measuring stick that changes.
You can value a house with the measure stick "dollar" or BTC, but that doesn't mean that the market cap of actually existing dollars include that value of course.
You can also measure the value of your house in apples or eggs or loaves of bread. Anything that has a certain value, can be used as a "measure stick" for anything else that has value. A currency is no exception to that. This essentially comes about because of the transitivity of prices: if asset A is worth x times asset B (that is, if on the free market, you can trade A for x times B or vice versa), and if asset B is worth y times asset C (that is, if on the free market, you can trade B for y times C), then: asset A will be worth xy times asset C.
Because if it weren't, by going in circles you could get an arbitrary amount of value (arbitrage).
Of course, this is assuming totally liquid markets, which in reality they aren't, so transitivity of prices is only approximatively true.
But that means that you can measure anything against anything else.
Mind you, because markets are dynamical, prices change all the time, exchange rates change all the time. Transitivity is valid, but only if you take all prices (exchange rates) at the same moment. Tomorrow, the values of the coefficients x and y will be different, but a priori, transitivity will still hold with these new values.
So a "measure stick" of value can be any asset.
And now you see why using a measure stick doesn't mean anything for the market cap of the asset you use as a yard stick.
You could just as well measure the value of your house in eggs, but that doesn't mean that the market cap of all eggs in the world include all houses.