Blockchain will be used not only in gambling and a payment gateway, but also it will be used on every branch of life. We have to wait to see what happen finally.
Well, the OP was not asking about blockchain uses but he was asking if blockchain could the only best option gambling gaming industries which I will say yes because in the situation where trust is needed while cheat is totally not acceptable it will get if blockchain was used.
It's already applied to some online crypto casino's and if you will hear out 'crypto casino' there will be a thinking that it's built through blockchain. I'm not against that blockchain will be used in every aspect of our lives.
But yeah, it's different and data inside the blockchain network can't be changed so it's really going to help who will adopt it. Abusers can easily caught out if the technology they run is blockchain. More improvements will be done and it's just getting better.