Everything with a beginning has an end, so the supremacy of Bitcoin will not last forever. That's reality. Hope for you it is distant in the future.
It's going to be in the very distant future if 'stupid' coins are being released like the ones that we had/have so far.
It's obvious that nothing will last forever, but it depends on how long it will last. Look at banks, Microsoft OS dominance?
Also it seems like people don't get this forum/it's name at all.
It's called BITCOINtalk for a reason.