some japanese blogger gave a conservative estimate
Post# of 997
I think Yoshitaka Kitao believes the amount will be much higher and is why he believes their new Exchange that will open in summer will become the largest exchange at the blink of an eye.
Someone also showed that Western Union processes over 32 transactions a second. If all were done via XRPL this would be 2.76 Million Transactions a day. currently the transactions are at 800k a day. at the height, in january, the ATH in transactions was 1.6mn. Guys, this only Western Union MoneyGram is a close second. The potential here for XRP is unmeasurable.
https://twitter.com/rippening/status/994303290002190336?s=19