Will VAT fees eventually reach Saudi, and GCC banks?

Most probably not. The finance/bank sector internationally comes under zero rated or exempt supplies. Hence there are no chances Govt will levied VAT on Bank sector.

Of course it will reach ksa and gcc banks

Yes, It will be implemented and charged.

If financial services are voted in respective country to be zero rated - minimal extra VAT costs. If exempt (or exempt with credit) - potential material VAT cost. Islamic Finance should be considered separately.

Probabile  No. In UAE, the culuture is different and well developed countries, strong in  economy.