The idea that new canon overwrites old canon no longer works. Star Trek with all it's different productions is in comic book land with the different series not agreeing with each other. It's saving grace is the ever present alternate / multi-universes that is part of all the series. Even the Abrams Star Trek movie taps into that.
But it does still work like that - just ask Christopher
, he writes the tie-in novels which, while non-canon themselves, are very much required by CBS to conform to the current
version of the Trekverse.
You can look at TOS in isolation and argue nomenclature and different interpretations of it all day long, but I guarentee you there won't be an official Trek product now that calls the Original Series Enterprise anything but "Constitution class." Just like the first Starship Enterprise is now Jonathan Archer's ship from the Enterprise
TV series, and James T. Kirk's father was first officer of the USS Kelvin as established in Star Trek
"Starship class" is obsolete in the greater Trek universe, just like Spock being "Vulcanian" or Troi experiencing every emotion she sensed in "Encounter at Farpoint". These things happen, it's not a crime.