It's very possible that the next 250cc motorcycle being launched in Thailand is the Sym SB250Ni Wolf.

The Sym SB250Ni Wolf is a naked sportsbike, with excellent performance (25 horsepower) and powered by a 250cc single-cylinder, liquid-cooled, 4-stroke engine, fueled by a modern electronic fuel injection and a smooth 6-speed gearbox.

The Sym SB250Ni Wolf

Nice bike when we can expect it in thailand?

The bike looks great. I like the styling, it reminds me of the MV Brutale and the Cagiva Raptor.
I've never heard of the manufacturer, so I don't think it will sell as well as the CBR or the Ninja 250's.
Why the single cylinder, underpowered engine?
Like the CBR and Ninja it will be no quicker than a good 125cc 2 stroke bike.
Any idea of the price?

The Sym SB250Ni is not as underpowered as you think, 25.5 horsepower at the right rpm can still be a lot of fun. Sure some old 125cc two-stroke motorcycles will be faster, but who wants to ride faster than 120km/h on a naked bike? (Not me, that's for sure...) Anyway, as two-strokes are baned in Thailand for new registration they are a dying type of two-wheelers...

We have currently no idea of the retail price, and it can even take some time before the Sym SB250Ni will become available in Thailand.

Sym is an internationally well known manufacturer of maxi-scooters, see the wikipedia page for more information http://en.wikipedia.org/wiki/SYM_Motors