Well, the 21 million BTC is a fundamental aspect of Bitcoin's design. Changing this limit would require a consensus from the network participants, which I believe it is unlikely given the strong commitment to Bitcoin's original protocol.
It also would alter Bitcoin's scarcity value and economic model.
Dimon's comment might be speculative or aimed at provoking thought, but it's good to remember the decentralized nature of Bitcoin that makes such changes pretty hard to make.
I believe that making such a change could mean a huge decrease on BTC value and even the loss of trust on the coin.
Yeah and Mr. Trump is not a fan of this as he wanted it to remain decentralized and of course we all wanted the same. Whales and institutions will surely dump huge amount of their Bitcoins if it will happen no doubt about that and that would be very disastrous to the crypto community and market.