If this will happen I will probably sell some and keep the rest. One thing is for sure, I will never sell all my BTC because I plan to leave some to my kids also. FIAT is garbage and it's not worthy keeping more FIAT than your needs.
Of course Iwould do the same thing to keep my bitcoin too but currently I am struggling to have my own kind of bitcoin so I am wishing that if ever bitcoin will going to hit a market value of $1000000 I hope it shouldn't be today or next month and I think not the end of this year because even the bitcoin price today was high enough and I couldn't afford it for now so much likely I would miss the sky rocket.