first off you asking for thermals to see trough smokes is only going to encourage people to sit even further back with a sniper rifle and play "high contrast immersion gaming"... i can already imagine how horrible gameplay would feel on the more open maps with 10-25 people sitting somehwere in a bush with thermals and the railgun....
secondly if DICE were to actually do this then they need to give everyone the option to add magnesium powder to their smokes as to make them appear like a white cloud to thermals... you know as a counter.
in the end this will hopefully never happen because it will not add any value to the moment to moment gameplay.
My personal opinion, DICE decided to just tease, please the mechanics and the foot soldier. What is the useful value of the NightBird thermal imager when it is available to the passenger? Why was it given to the NightBird, but not to the shooters of attack and stealth helicopters? They also did not give the opportunity to put instead of optics in the main gun of the tank, they were afraid that the tankers would bend the infantry like a BF4.
They did, but through one place, as they say.
