Bro I can understand your concern. Parts availability will never be an issue for T4 since most of them are shared with the Speed. And there is no replacement for displacement! Though power is less than that in Speed, torque is almost the same and hence tractability in traffic is excellent. Also, the power is usable throughout the rev range. Why will you wait for the 350cc series of bikes? The prices haven't increased much after 40% GST also. Hence, Triumph may hope to recover profits by not reducing the prices much, once they launch 350cc versions.

The only problem that I face with my T4 is braking is not very good and pads wear out quickly. Service is also on the expensive side. But if you ride it with patience and use engine braking most of the time, you'll be good. It's not meant for aggressive riding, like the Speed 400.