100 Exceeds were sent to get the dragon slayers. Happy, Carla, Sting, and Rogue are all Exceeds who abandoned their missions.
What about the other 96 Exceeds who are unnamed, unseen, and out of the picture? Does this mean there are 96+ more dragon slayers in earth land?
There is NO information regarding the said 100 Exceed eggs sent from Extalia, any answer would be speculative as best.
Only information we have on them is that the Exceeds from Edolas are now looking for them. I doubt if we will get any information regarding them either. They were just meant to provide the plot device for the history of Happy and Charla.
I found the answer after nearing the end of that arc in season 3, episode 95 "Lisanna." This is after everything happened in Edolas and the entire war was won. The exceeds were sent back to Earth Land and found themselves homeless, they were told the truth about their eggs that were taken from them and sent down to Earth Land to "kill the dragon slayers." Being told that was all just a ruse and was a cover up for the real fact that the eggs were sent to Earth Land to carry on the Exceed race because the queen had foreseen the future and saw Extalia falling to Edolas. This made them think of sending eggs into Earth Land as to save the race and to be sure to continue on their legacy.
Dragon Slayer magic was a rare type of magic. I doubt there would be more dragon slayers other than those already introduced. Also to be noted is that only dragon slayers taught by dragons have Exceed partner.
Natsu Dragneel was taught by Igneel. Partner Happy. Gajeel Redfox was taught by Metallicana. Partner Pantherlily. Wendy Marvell was taught by Grandine. Partner Carla. Sting was taught by Weisslogia. Partner Lector. Rogue was taught by Skiadrum. Partner Frosch.
Other dragon slayers who became one due to lacrima being embedded into them don't have Exceed partner.
Laxus Dreyar, thunder dragon slayer. Cobra, poison dragon slayer. God Serena, multiple element dragon slayer.
Another thing that they have in common is that all dragon slayers with Exceed patners all was sent into the present from the past using the Eclipse gate.
Thus, if we go by this pattern, the other Exceed (of those sent to Earth) are all partnerless because in the present dragons have already go extinct, with the exception of Acnologia. Only 5 dragon slayers were sent from the past and all those 5 have their partners already.
Acnologia was originally a human taught by a dragon. In this sense he is the same as the other 5. However, he is never seen with an Exceed partner. It is safe to assume that he don't have one.
As for whether there are more dragon slayers than currently shown, we can't say for sure because the story still goes on.
