Who will be the largest Bitcoin vendor because they are trusted.

But they won’t be the only vendor. There is no license required that gives them a monopoly on bitcoin. If they serve a market segment, great! Others will use something else. Bitcoin is entirely open - it’s a protocol.

So is EDI used by banks with other currencies. I am old enough to have used it :)

That's fine. Bitcoin adoption by these institutions makes it easier for people to receive it who don't actually want to hold it.

Still, note that you don't need Paypal to move Bitcoin.