Taekwondo will never become 'just one' as in 'just one organization', or 'just one style'.
If it DID... it'd stop being a martial art and it'd turn into something else.
In martial arts, since time immortal, every individual master, has put their OWN stamp on the arts of their choice, and taught them to their students. Then those students have done likewise... learned what they could, then added their own 'stamp' if you will to the art, and raised their own students, who went on to do likewise and so on.
Frankly, I don't WANT to see the WTF and ITF and ATA and all the organizations start merging... because WE WILL LOSE SOMETHING SPECIAL with each merger.
It's the DIVERSITY that makes our art strong.
I have studied at length, two styles of Taekwondo, (The 'original 20' forms of the ITF and the Songahm style), and have dabbled with WTF forms and at least reviewed a couple of others.
The techniques are all the same folks... it's all Taekwondo.
The patterns might be different... but we're cut from the same make of cloth. There's no better, or worse... there's just Taekwondo... and if it's taught by someone who knows what they're doing... it can change lives for the better.
That's the bottom line for me.
Since some are sharing their forms, I'll share the ones I've learned in order of my learning them.
Chon Ji (White belt)
Dan Gun (Yellow belt plain to yellow belt with 3 green tips)
Do-San (Green belt plain to green belt with 3 blue tips)
Won-Hyo (Blue belt plain to blue belt with 1 red tip)
Yul-Gok (Blue belt with 2 red tips to Blue belt with 3 red tips)
Joon Gun (Red belt plain to Red belt with 1 black tip)
Toi-Gye (Red belt with two black tips to Red belt with 3 black tips)
Hwa Rang (1st Degree black belt --recommended---plain black belt)
(Note... at this point I had 3 testing cycles or 6 calendar months to pass another test to make my 'decided' 1st degree black belt, OR I'd revert back to a red belt with 3 tips)
Choong Moo (1st Degree black belt decided with uniform trim or trainee instructors' stripe)
(NOTE... ATA was rolling out Songahm forms by this time and to ready us for more challenging forms that black belts would be doing under the new system... I was taught two more forms, which were the 2nd degree recommended and 2nd degree decided forms, which were...)
Gwang Gae ---(2nd degree recommended form prior to the rollout of Songahm style)
Po-Eun ---(2nd degree recommended form prior to the rollout of Songahm style)
By the time I made 1st degree, the Songahm style was gradually rolled out... I learned Songahm 1-5 and In-wha 1 and 2, before I dropped out...(I was a teenager and got interested in girls and a few other things)
I got back into things formally in 2004... and refreshed my knowledge of all of my techniques AND all of my past forms up to Po-Eun... THEN I returned to formal training in the ATA, and learned 'in order' in the space of a year...
Songahm 1 -White belt form
Songahm 2 -Orange belt form
Songahm 3 -Yellow belt form
Songahm 4 -Camo belt form
Songahm 5 -Green belt form
In-Wha 1 -Purple belt form
In-Wha 2 -Blue belt form
Choong Jung 1-Brown belt form
Choong Jung 2-Red belt and red/black belt form (red/black is 1st degree recommended black belt in the ATA now)
Shim Jun -1st degree decided black belt
PLUS the single ssahng jeol bong and single bahng ma ee weapons forms.
Since then, I've learned Koryo from a WTF friend of mine, and studied boxing under a local former professional boxer.
I have also audited the Taegeuk and Palgwe forms, and they are quite interesting. I've also had a look at the Pyung-ahn forms, which were used in TKD training well before I was a twinkle in my dad's eye.
It's kind of awesome really... to look at all the different forms in the TKD world and then to watch people trained in them, show them off.
Taekwondo is an awesome martial art, regardless of the style.