There have already been charities financed in crypto. We can't really talk about the future for Bitcoin or the purpose of use, since it's a currency.... On the other hand, we can expect that adoption by the general public will increase and that more and more of our payments will be made in crypto ! More and more good causes and less and less bad causes !
If you are donating money, then the receiving party no longer cares in which format you sends that money. Ever since Wikileaks started accepting Bitcoin in 2011, we had thousands or even tens of thousands of charities accepting Bitcoin payments. Even Wikipedia (which took an ant-Bitcoin stance earlier) was begging for BTC in 2017. But one of the issues that we face in our country (India) is that only donations made in fiat currency are liable for tax breaks. If you are donating BTC to some charity, then you can't claim tax breaks for the same. So whenever I make some donations, I first convert my cryptocurrency to fiat cash, and make payments using these funds.
That's the right decision. If you can make a donation of fiat money, then why use Bitcoin. This is even from a security point of view. I do not use cryptocurrencies as a means of payment. It is better to trade cryptocurrency or keep it for the long term.