I doubt very much that altcoins will make the competition of bitcoin. Bitcoin has a long history,a large community, miners, manufacturers of ASICs, it is a large and profitable business.Hardly the balance of power will ever change.And if something bad happens to bitcoin, it can cause a collapse in the entire crypto market.
No one has the exact answer for this as market is diplomatic. I agree BTC is a strong coin in the world anything can happen in future as ETH gave toughest fight to BTC last year. Bitcoin dominance is more comparing to other Alts. Lets wait and see.