Nothing special would happen; that would be a natural evolution due to the fact that some altcoins have better tech specs than BTC.
Yes it will not be a big issue, because up and down is always there in competition, we can see that people are also investing money in Etherium and other crytpo currencies, they have the expectation that the coin they have selected will compete with any other cypto currency and will overcome them, may be it will happen in future, but it does not mean that it will bring such a big revolution in the market, i hope that it will be a normal process.