We don't know that, remember there is a lot that they haven't shown us and like it or not gen 1 Pokémon are more marketable simply due to nostalgia reason.
Heh, the design looks cool. Though I am unsure if I will make my Charizard Gigantamax .
Actually, it would be interesting to see if the Charizard that I had breed for generations actually has the means to Gigantamax as not all Pokémon can do so. 🤔
Yep, it also shows the creativity of Game Freak as Charizard has 4 forms as they are still able to come up with new designs for him.
May Charizard continue to appear in every generation and get more new forms.