Come on guys its simple so why is there an argument....The order of chakra ability with the new expansion now goes....
Lowest-Affinity for x element
-Affinity for x element, and ability to use y element
-Affinity for x element, and mastery of y element-(Jounin level) This is nothing special.
-Affinity for x and y element-Bloodline Limit-Ability to fuse elements required. Usually a trait you are born with.
Highest-Affinity for x and y and z-Bloodline Expansion-Fusion of three..
The only mystery is Tsuchikage said he learned the secrets but learning would imply he was not born with the affinity...So this would also mean that people have the ability to Learn to combine elements although it is so rare only 2 people were able to combine 3.
Now I am not a Naruto fan boy but the reason I feel Naruto will be able to one day combine two elements at the bloodline level is he is the type of Ninja that learns to break rules with "gimmicks" I guess is the best word to use for it. Where a Ninja with a bloodlimit can combine elements because they are born with it, Naruto has the ability to learn to do it. Take for example his Rasengan....First he was able to learn to manipulate his chakra without adding in the required control requirement(Shadow Clone) Second-He was able to add in Wind chakra to the rasengan which is like walking in too different directions at the same time...(Shadow Clones); the best way to do two different things at the same time is to be two people. Now with that being said Naruto is the son of a clan of people with amazingly high chakra and endurance from of the whirlpool village. Now if this isn't enough foreshadowing Naruto learning to use water then the fact that Sasuke uses Lightning and Fire-Lightning Affinity and Fire "Clan" Affinity- adds to this. In the world of Naruto Water>Fire>Wind>Lightning....Now every villain is the opposite of the Hero and Water would make Naruto the opposite of Sasuke...Ungifted and Learned to be great with Wind and Water vs Super genius that just woke up and could use lightning and fire....Now going back to my original point....Naruto's ability to find ways around different tasks....Combining his elements-Shadow clones is his answer to everything...and why wouldn't it be his next answer? Shadow Clone 1 Wind Shadow Clone 2 Water combination? He has a chakra ability that makes his stamina almost limitless combine with Sage chakra and ninetails chakra...using two elements will not drain him to learn.... Trust me the Hurricane is coming... as for Bloodline Expansion I don't see this happening because its unnecessary to Naruto's development as a character. Hurricane jutsus have been alluded to since the beginning and I don't think there is anything that will stop Naruto from being able to use it. But combinations are rare for a reason....its hard...Naruto is the type of character that makes difficult things easy with a "gimmick"....he will use it again....