I think it makes sense that we will see numerous variations and configurations on the lightsaber as time goes on. It is really no different than the variation of bladed weapons we see in real lifehttp://www.ew.com/article/2016/01/15/star-wars-rebels-video-lightsaber
Ezra Bridger, the young Jedi in training (voiced by Taylor Gray), ignites a crossguard lightsaber similar to the one wielded by Kylo Ren in the new film – only this one is green and seems to be of much sturdier construction.
We know from a Disneyland display of props for The Force Awakens that Ren’s saber, with its distinctive laser quillons, was an “ancient design” that the the Darth Vader obsessed young man recreated himself in crude fashion. In the upcoming episodes of Rebels, Ezra will apparently encounter a similar weapon.
We have already seen a double lightsaber and well as ones with curved hilts (Count Dooku and Asajj Ventress). A claymore style saber was all but inevitable.
About the only thing that seems to be consistent is a straight blade.