What worries me most is banks. Banks will want to use this for “security”, shutting out everyone from their own bank accounts unless they're using a proprietary operating system and browser (which ironically makes them less secure).

And even if some banks don't, and I can simply take my business elsewhere, how will I know which bank to take my business to? Presumably they'll only require WEI to log in, not to view the bank's website as a guest, so I'll have no way of knowing whether the bank is actually usable until after I've moved my money.

It will probably be a decade before they throw the switch, what with all the old people using old computers, so it'll be a complete surprise when it does happen. One day, in 2033, long after I've forgotten about this issue, my bank will suddenly refuse access until I “upgrade” to Chrome or Safari…