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 think Messi should not have considered his commitment to the club economically. They could have agreed on a symbolic figure, since Messi can still earn big money through advertisements. Barcelona might not be able to give him the salary he wanted, but I would expect him to be more loyal to Barcelona.
What commitment are you talking about? Do you know that till today, there are still some outstanding payment that Barcelona should have paid Messi but chosed not too because they think it easy for them to hide under the durex of finacial stress and debts and I don't think he has press them ever since he left the club, if there is any charges since he left Barcelona, it will be all over the Media by now, so tell me what you mean by commitment if there is any loyalty that is closer to what he has done in Barcelona.
If you don't talk about the past, discusing about the presence is useless, Messi has paid his due in that club, he has done what nobody could do, before anyone will emerge as the highest goal scorer in Bacercelona, it will take more decades after he must have retire from football.