There is correlatable evidence to demonstrate for 2 futures jobs for FF14 based on what we have gotten in Stormblood and it can easily be discovered in any major hub with a market board. Now for some context.
The Facts:
1. We all know that jobs share gear beyond level 30. Casters share gear with casters, tanks share gear with tanks, healers share gear with healers, so on and so forth. But there is a subtle difference in relation to 2 current DPS classes...Dragoon and Ninja.
2. Back in HW, Monk was also locked into this arrangement with DRG/NIN...but SB changed all that. How you may ask? With Samurai of course. What do you mean? Well, Monk from ARR and HW did not share gear with any other job...now it does. That job being Samurai.
3. So what does this have to do with DRG/NIN? Well as was with Monk, these 2 jobs do not share any left side gear other than belts with any other current jobs. Dragoon gear like helmets, chests and feet all are only equipable by Dragoon except for the rare occasions of DOW pieces. The same applies to NIN.
4. So lets look at DRG, what kind of class is it? DRG is a STR based melee DPS with most gear aligned as heavy appearance. How about NIN? They are a dex based melee DPS job with most gear aligned to medium/light appearance. Do any of these jobs share gear with any other job when it comes to the left side other than belts? Nope. That is where we start getting a solid analysis.
5. You may then ask, what jobs have been in FF in the past that can be assumed as a STR based melee job using a heavy appearance or DEX based melee job also using a medium/light armor appearance? That is where it get interesting....
*Now I will mention for anyone going to critique this next part...yes, SE may come out with a original job to FF14 with no relation to past versions. Yet we know it will be a STR based in line with DRG gear and also a DEX based aligned to NIN gear. I will not speculate on exactly what that will be as I am not a soothsayer. I will give my opinion to what I hope it will be.
Possible Jobs Based On Final Fantasy's Past:
Similar to Dragoon: This is pretty easy. If you go to http://finalfantasy.wikia.com/wiki/Category:Jobs and do a basic search for all jobs in relation to this...there are only certain ones that align with Dragoon. I will let you discover that on your own.
I personally feel like Beastmaster would be a perfect matching to DRG in relation to gear sharing. Why? BST sometimes in past FF games was a user of heavy armor in appearance and also used Melee weapons such as a one handed axe.(Yes I know they use whips also, that can make them paired with NIN then since whips are a hybrid ranged/melee weapon)
Lastly, we have Summoner. Someone will make the comment "YP stated that he hates pet based jobs". So? YP fav class is BLM as everyone knows. Does that mean he will only make caster classes from now on since he likes those but hates others? Of course not. It make rational sense for SE to make a counter pet job to SUM that is the polar opposite as they have demonstrated with tanks/healers/DPS. WAR is about Burst and HP pool, PAL is about Defense and Blocking...and for the most part DRK is a mix of the 2(or at least it tried to be in my opinion).
To me, BST as a mirror to SUM would make sense. Think about it, a melee based pet class polar opposite to SUM, a caster based ranged pet class.
Similar to Ninja:
As I have already explained the same concepts about Dragoon...I need not go over it again.
I believe that Dancer will be the mirror to NIN. Why? NIN is a dual wielder, as are past versions of DNC. Now they may use DNC with fans...but it still would not negate how DNC who "dances" by every logical regard requires dexterity.
So the next time you go to the marketboard in you main city...look at the gear that is worn on the left other than belts for DRG/NIN and ponder...what will be paired with them in the future? Only time will tell....