Was this not also your thread back in 2015?
The actual foreign exchange market, where actual transactions take place and actual funds move from one bank account to another, is a very different entity to retail trading on leverage via brokers, where phantom money that we do not have is “exchanged” with another party for “money” denominated in a different currency that also does not exist.
Genuine foreign exchange will exist as long as countries have different currencies and allow exchange to take place, and there are individuals/enterprises wishing to do “business” between those countries - whether this “business” is tourism or investment or commercial, etc.
What we do in retail “forex” is entirely separate from that real foreign exchange and could end tomorrow without changing that underlying real market (apart from some minor issues such as liquidity, maybe, etc).
The point is, I think, that no one is really going to be interested in trading real cash with no leverage unless they have a very large sum to move around. So if our retail business is regulated out of viable existence then retail trading will cease as we know it - and basic, genuine, foreign exchange will continue.
Maybe a more pertinent and realistic question might be, not how long is the forex market going to be around, but how long is oneself going to be around in it?