All cellphone batteries can be what's called "fast charged". It's not really fast charging - the fastest charging I've seen is about 80% of what the battery can take. The charger circuitry in the phone has to be able to do "fast charge", and almost all phones will be able to from now on. (Batteries can be charged at up to their capacity, known as a 1C charge. IOW, a 3000mAh battery can be charged at a 3000mA rate. Most "non fast charging" phones would charge that battery at about 1000-1200mA. But the old batteries can still be charged at a full 1C.)
So will the S7 have fast charge capability? It has the chipset, so it would be stupid of Samsung to disable that function. (They made 2 disastrous decisions - no SD card and a non-removable battery - and it cost them in sales. I don't think they'd make a totally stupid one like disabling quick charge.)