It is impossible to give an exact time frame I can see this happening in the near future, unless we see a massive take off for Ripple, but honestly I see LTC going places. Perhaps it even has the potential to unseat ETH someday, but let's not get ahead of ourselves. The reason that I believe LTC will take over is that it is a superior coin for consumers. Ripple has one function, bank exchanges which gives it value.
Precisely, LTC is a global algorithm. And XRP is highly specialized. It is not correct to compare them from the technical point of view of the point of ripening. But from the point of view of making a profit, I can say with certainty that Ripple is much nicer to me