> I think there's a danger of that, at least if countermeasures are not easily available

Note that the era of free navigation is recent and short. Countermeasures would certainly emerge. But shipping wouldn’t stop.

> Are there enough military ships to do the escorting?

For critical passage, yes. If Iran is just taking pot shots at any ships anywhere, you basically have to actually blockade it.

The current situation is very dangerous. A global disruption in shipping would lead to an economic crisis that could start WW3 (imo).

Also the US and Europe would be pretty fucked since we depend on it much more.

China could still get resources from russia and is much more self sustained.

Also China and Russia want to break the us hegemony.