I don't know why people care too much about total marketcap between XRP and ETH. What's benefit for you if ETH take on/overtake XRP for 2nd place again?
In short-term you might see the market cap of XRP will be more compared to ETH but in long-term, you will see who is going to be better. With the active developments and mass adoptions will surely raise the price of ETH and as well as the market cap we need not worry.
I don't really see the point of comparison of market capitalization of both coin/token, each perform differently and offer different services, their distinctive character will determine which one people will find more useful in real life use case, at the end general adoption will really determine which will have the higher cap.