Indeed, that may be the case. I just used exchanges because it was a good example of trade being abstracted away from the blockchain.

But it isn't as much to do with the technology as the dynamics of liquidity in general. This also speaks to your point about "credit" and whether it's good or bad.

Let's say you're in a salaried job (I don't know, you may well be for real). Lets say you get paid monthly. So a couple of days before the end of the month you will have worked a full month's salary which will likely be recorded in your employer's books as an "accrual". i.e. that's a figure that will appear in the liabilities section of their balance sheet along with other accruals such as goods received not yet invoiced etc. Once those goods are invoiced and your salary paid, those liabilities will get transferred to cost and disappear, but new accruals will form so we are always in a state of flux that requires a credit "headroom".

Those accruals will aggregate in the "net assets" bottom line on your employer's balance sheet which will place it in an overall state of debt/credit, regardless of whether they maintain any state of banking indebtedness. (Strictly speaking, positive or negative equity, but since equity is always owed back to the shareholders I've taken a liberty with the terminology and just described it as debt/credit).

The aggregation of all these bottom lines amounts to an aggregate state of credit for the entire economy, some of which will be monetised (because there are always uses for high quality collateral) and some will exist in records which will find their way into the national accounts and that will be monetised instead.

That is the NORMAL state of affairs. i.e. if you take a snapshot of any economy at any given time there will be a huge "headroom" of credit which amounts to the oil in the engine that it can't do without. In fact, as I've pointed out, the credit economy accounts the majority of the money supply not the minority.

The exchange is just a symbol I used for this phenomenon that - handily - happens to fulfil both a metaphorical and real role in cryptocurrencies. Have a look again at that money supply graphic and you can see how the money supply "inflates" like a tyre, well beyond the boundaries of the base collateral supply. Running an economy without credit would be like an engine without oil or a car without tyres -impossible.

I mentioned earlier that the effective liquidity of Dash is well over what the blockchain coin supply reports due to inflation in the credit markets such as exchanges and that we have to "add" the exchange liquidity to the blockchain total arrive at the total economic money supply. (Lets say for talking's sake that in our little "toy" economy, blockchain tokens are "M0" and exchange liquidity is "M1". Then total Dash money supply would equal = M0+M1).

You rightly point out that exchanges might become decentralised and therefore M1 would disappear. What I'm saying that this phenomenon (of credit inflation beyond the base supply) is so natural, so ubiquitous and so necessarily that if adoption continued to grow, M1 would simply find other fertile sectors of expansion - i.e. any offchain liquidity at all that was "denominated" in Dash would qualify.