In terms of web traffic iOS is a large enough percentage that sites have to cater to iOS/Safari. Since Safari doesn't support all of Google's latest fingerprint/tracking friendly web APIs most sites won't hate their content behind them. As soon as a "just install Chrome" banner is viable on mobile there's no reason websites won't be flooded with Chrome-only features.

A Chrome-only web will edge out not just up to date competing browsers but any older iOS and Android devices that can't run top of tree Chrome.