So if I understand correctly. You are saying that all the public chains will merge into one pool of liquidity due to a ~ 0 transaction cost environment for moving liquidity between chains but that monero will be somewhat protected from this since moving liquidity between chains will have a sort of friction resulting from the transaction cost resulting from information leak. Do I have this right?
If so than I think it is not an apples to apples comparison. Couldn't many more opaque chains come into existence and have 0 friction with monero and rob us of our liquidity just like happened to bitcoin?
When you say "just like happened to bitcoin" I assume that "under the hypothetical scenario of vanishing exchange costs" is implied. I won't quibble over the relation between information and utility; your abstract suffices.
There won't be a vanishing cost XMR exchange unless XMR is modified specifically to allow it, with suitable scripting or some hard-coded facility, e.g. for lightning. The technical fundamentals need to change in order to magnify the hazard you describe to the point where it is material to valuation. (That is a dead-reckoning estimate of a quantitative factor, and certainly would benefit from additional facts or logic.)
Because one [ZEC] was started from a company and can pitch other companies, while the other [XMR] is a full open-source project.
That is why the (centralized) governance risk of ZEC is so much higher than the (decentralized) governance risk of XMR. The market prices that in, I think. Much of the money in BTC is well aware of this factor. However, prices are set at the margin, and it is also most of the reason for the 20% development tax on ZEC. I don't think that factor is properly priced in to the marginal clearing price. Eventually long-term holders will feel the pain of realizing that buying ZEC is effectively giving away 1/5 of their wealth, and reserve demand will suffer as a result. If ZEC had trustworthy governance, I would have bought some as a diversifier, but I just can't suffer a scam lightly.
It remains no less useful as a transaction medium, if you don't care about TLA surveillance, and don't hold it too long, but then the same could be said of Doge.