I strongly believe that some other coin will dethrone bitcoin sooner or later. It might not actually dethrone it but its impact night greatly impact the value of bitcoin negatively.
It's a bit similar to USD: everyone knows that USD is doomed, but other fiats are depreciating towards it, so you have to use USD if you want to be in fiat.
My feeling is that alts will further depreciate towards BTC as a whole, since there are so many of them, new arrive every day and you cannot predict the winner.
And even though in the end BTC is doomed, there's no safer option than to be in BTC if you are in crypto.