Bitcoin will remain the only solid coin. The only coin that survived for the longest time (other coins can't claim this unless they invent a time machine).
There will be alts that pump really hard and make people millionaires, but no alt is going to surpass Bitcoin's strength and solidity. No coin will get a bigger marketcap. In the long term people holding 21+ BTC will be rewarded by history with rich-tier status for seeing the value in it before most people did. Do not let the FUDsters trick your mind or the trolls try to derrail the excellent job being done by Core devs.
Let's continue then our path towards inevitable triumph.