any reason why all providers will eventually put users behind cgnat? does this mean that there will no longer be static ip or it would a paid service?
Not only would there be no static ip, there would be no dynamic ip, you would have a shared ip which is worse - no inbound connections, no port forwarding etc.
IPv4 is not suitable for the modern Internet, there are simply not enough addresses. As the addresses are in short supply, their price keeps going up.
For instance, a provider in Australia moved their customers to CGNAT because of the cost of IPv4: https://www.itnews.com.au/news/aussie-broadband-wants-to-stop-buying-extra-ipv4-addresses-511902
All mobile providers are already using CGNAT, MyRepublic use it, according to posts here ViewQwest are also moving some customers to CGNAT.
In less developed countries such as Myanmar, ALL providers already use CGNAT. Home users simply have no choice at all, business customers can still rent static IPv4 but the cost is high (~500 USD per month or more on top of the base price).
Newer providers also generally use CGNAT, not because they want to but because they have no choice.
Even in a saturated market like Singapore, where incumbent providers already have enough IPv4 for their customers, providing an expensive resource to a customer paying <$50/month does not make business sense. There will be a temptation to sell the address space, or to start charging customers high fees for it.
It's not a question of if it happens, but a matter of when. That's why we need to move as much as possible over to IPv6 now so that we don't get caught off guard when CGNAT inevitably rolls along.