Basically if Laporta wins in March, which I think he will, he will stay.
He will only leave for City or Newells but the only way I see Messi seriously considering leaving is if Freixa somehow wins by some miracle. I am sure he and all the other big earners will agree to more wage cuts to help the books out for the new president, especially if it is Laporta.
From the football perspective, I think he is clearly enjoying his football again because he finally has some players who are on the same wavelength instead of Denis Suarez and Andre Gomes.
If Laporta wins and we win any trophy this season, I would be willing to bet money he will stay.