My comment about transaction fee is correct.
But I told you that you don't need to sell BTC until you see the transaction fees rising too much. The fees won't rise overnight. It will be a slow process over the coming years.
Yes you will end up buying an altcoin eventually some years from (or cashing out to some fiat or other asset). You will have no choice.
Are you aware there can be 2 scenario playing out?
Scenario A: Fee rises along with bitcoin price within a fixed percentage. So if the percentage is 0.1% and bitcoin price is at $100,000, then the fee will be $100. And if bitcoin price is at $1,000,000, then the fee will be $1,000.
Scenario B: Fee rises regardless of bitcoin price. So if fee is fixed at $1,000 minimum, it will remain at $1,000 (minimum) regardless of whether bitcoin price is at $100,000 or $1,000,000 (or even at $10,000, effectively meaning to say the fee is 10% of transaction value).
Which scenario do you mean will play out? Or is there a scenario C, if so, how will it play out?