I've never heard any rumours that Neymar might return to Barcelona. Messi as far as we know rejected the idea himself because he found cutting other players' wages for his presence unacceptable and it was indeed a wise decision. In the end Barcelona could theoretically afford it anyway by cutting other players' wages and their budget wouldn't suffer much, and the worst part is that they were prepared to do it despite the fact that they are already very much in debt
I don't think Messi is too concerned about cutting other players' wages. If that was his intention, he would have stayed. Messi has set his sights on certain goals for the final years of his career. He had won all the trophies with Barcelona, and leaving while still at the peak of his career was a wise decision. Furthermore, the compensation and salary at his new club are quite attractive, without the added pressure during matches. This is in contrast to Ronaldo when he returned to Manchester United; I don't think it was a wise decision given his previous successes. Fans tend to compare and have high expectations, which can be a significant burden for a player preparing to face new challenges.