Well if you heat the sodiumbicarbonate you will get thermal decomposition, so you'll get 2 NaHCO3 → Na2CO3 + H2O + CO2 and if you really turn up the heat (say 1000°C) Na2CO3 → Na2O + CO2.
I'm not sure if this leads to any reaction with the Potassium ferrocyanide however. It might have something to do with Sodium Ferrocyanide, but I can't be sure.