The only way it could work is if you kept the important trio at the front and had ranks of Jedi appear behind them (thousands) but with the prominant prequel Jedi nearer to the front (a bit like the ghost army in Return Of The King).
That could work as a story detail because now Luke can call on the collective wisdom of all the Jedi that have gone before him but it might look very messy on screen and I'm pretty sure the story doesn't need it.
The Force is now in balance because there is just a master and an apprentice (which is why I still think if Luke trained his sister things would turn nasty in the Episode VII GL refuses to make) if Luke is getting permanant backup from thousands of dead Jedi that throws the balance off again to the light side (not unless they pinch another idea from Dune and have Luke/Leia be able to see dead Sith as well like Alia's ancestoral memories bringing back the Baron Harkhonnen).
In TPM there are thousands of Jedi and two Sith, a master and an apprentice, at the end of ROTS there are two Jedi and two Sith both master and apprentice. In ANH Ben takes an apprentice and Vader corrects the balance by removing Ben. In ROTJ Yoda dies correcting the balance Vader kills Palpatine but by returning to the lightside he has unbalanced the force again so he dies as well leaving just Luke to begin from scratch.
They could be just be turning up to say goodbye but that buggers up the line from Obi-wan, "Yoda will alway be with you".