No, George Lucas explained that to balance the Force you needed to destroy the Sith, that's it. The Light Side brings balance, the Dark Side destroys it. Luke will refound the Jedi and a new Galaxy with plentyy of Jedi and no Sith will be well balanced.
To quote GL himself from the Japenese magazine interview he gave:
"In each of us we have balance these emotions, and in the Star Wars saga the most important point is balance, balance between everything. It is dangerous to lose this... it is obvious to [The Jedi] that The Sith are going to destroy this balance... at the right time a balance may again be created, but presently it is being eroded by dark forces "
So there you go. The Sith (and the 'Dark force' they represent) will destroy this balance when they wipe out the Jedi, by destroying the Sith the balance will be restored.