Footage from 6 months ago showed Rangers with a pet. For some background on why this is a problem: Some people absolutely loved the idea of a Ranger class that was a simple bow and sword-wielding Aragorn type. Unfortunately, the Ranger class is uniquely built around the pet, meaning the ability to play as a light-footed melee fighter and archer was hindered--pets make up for a portion of your assumed tankiness and damage, so you can't avoid using them as a Ranger without taking a huge pointless hit to your effectiveness. Combined with the state of AI, Ranger is a class often picked up by people thinking they can live with it, only to realize they'd be happier playing without a pet (at least for some of the time).

Now, as the Druid was shown with a pet all that time ago in the preview, some suggest this (arguably the biggest Ranger disapointment) is now being addressed, and the Specialization will not be a way to fight alone (gaining something else like a stat bump in the place of the pet). However, not only could this have been changed since the original trailer for HoT, there are other possibilities for the Druid. You might have a way to merge with your pet, or even control your pet remotely while in a safe location, like a Warg.

It's not likely though. ArenaNet built the class around the pets, and tossing that out the window with one new trait line would be very difficult. All the pet traits and skills would need to be adjusted to match up with the new stat buff or transform buff, similar to the way Necromancer's Shroud traits were adjusted for Reapers, and the already unique pet controls may find themselves becoming even more complex.

TL;DR - People don't want pets on their Rangers (all the time) and think Druid could have but will not change that. Which is good, because they seriously have no reason to expect that massive of a shift in gameplay.