Bitcoin may become significantly less volatile in the future when its price rises well. This does not mean that its price will no longer rise, it will continue to rise, but this will happen without big fluctuations, there will not be a strong increase and a strong fall.
If, at the same time, bitcoin is not interesting for investors for speculation, then it may become interesting as a means of payment, and I will be very happy about this. But I think that many investors will still buy bitcoin because it will be a stable asset that will grow and save money from inflation.
But why will it become stable in the future? People won't just stop trading it. More people will invest in it, more people will short it etc. And I don't see that this trend will change any time soon. That's why I don't see bitcoin as a payment method in the future.