What do you mean saying that ripple will replace bitcoin? If it will replace it on coinmarcetcap - that is only numbers, give me 1m$ and I will make the coin from rank 900-1000 the coin number one on coinmarketcap. If you are talking about ripple replace bitcoin as a currency and all cryptos will be compare to ripple - I'll leave this market, where centralized currency took control ove decentralized one.
Answering your question - nothing special will happend. Except all this mining equipment and all THs will be forced to find new coin with same algo