I have two ESP8266 and two Feather Huzzah ESP8266. I will keep my actual project with the Arduino UNO and add later the ESP8266 to it for the wi-fi.
The ADS1115 can be used directly with the ESP8266, no changes needed.
An ADS1115 and thermistor (or pot) is not a very good match.No ratiometric relationship between thermistor and reference voltage.
Why not? I'm using Vcc as reference, the ADS gets the same Vcc on the input. I don't know how they internally create the reference voltages, but if this is not a good match, it's hard to think of anything that would be a good match as so many analog sensors give a 0-Vcc output.