In the next 100 years, do you think Governments will create their own cryptocurrency or digital currency that will replace fiat currency, i.e. coins, paper money, the paper dollar, etc.?
If it does happen, will it be like bitcoin or will it still represent gold like how today's money works?
They will do 100%. In fact many of them are already planing it or have already done it like Venezuela. In most cases it will be nothing like bitcoin or gold.
Btw are you seriously thinking current fiat represents gold? It actually represents dept as its printed to loan banks/corps/government/people and thats the reason its always depreciating.
If governments create their own crypto it will be exactly like current fiat. It will be based on dept and depreciating. They will print as much as they want depending their financial policy. It will actually be worse than fiat because it wont be anonymous and it will be easier to control so if you are against your government they will be able to close your accounts instantly.