I completed all the levels a month, or so, ago. Then, a new update to the game added a few more levels. Today is March 27, 2017. As of a few weeks ago, there are 3800 levels (on the Android version of the game). Future updates will, undoubtedly, increase that number. In this screen shot, you can faintly see the 3800 level emblem grayed-out in the background. Visit https://4pics-1word.info/6-letters/ for all the answers of this game.
I’m addicted to this game, so it was a drag running out of levels. Fortunately there’s multiplayer versions of the game. I chose League play. League levels start at level 15 and descend from there. If you vanquish enough opponents, you get promoted to the next level. I got down to level 1 and figured I was about to max out the game again . . . but when I completed that level — surprise, surprise — I was promoted to the “Legend” level.
This made me wonder what, exactly, is the pinnacle of league play. So I Googled it. That’s where I saw the OP question. So I clicked it and here I am.