This is not the issue of the future because bitcoin have already be an ideal currency and this is the reason why some governments and central banks are planning to create their own national digital currency.
Do you think that bitcoin will be spoiled by human in the future?
The only ways people debated bitcoin can be spoil are through quantum computer but it yet to be implement.
The second aspect is government ban but bitcoin is already winning over the government affection.
Should bitcoin use SHA512? Or something even stronger?
It can use SHA or something stronger but that will be determine by things happening in the miners realms.