Thailand is the second largest market for motorcycles in Southeast Asia. If Yamaha Asia is creating a model specifically for Southeast Asia it's very likely it will be introduced on the Thai market....
Import taxes not too high for a base model budget Yamaha?
For motorcycle with less than 250cc engine size, which is expected to change soon to less than 300cc, the ASEAN import rules, duties and taxes are different. Even if the motorcycle is imported from outside the ASEAN zone.
But it's difficult to speculate about the cost of a motorcycle which will be developed in the near future, they first have to build the Research and development center, so it can be easily a few years before we see an actual production motorcycle.
The Yamaha budget motorcycle which will be produced in India. See article New Global Yamaha Budget Motorcycle Developed.