Let me tell you that if Messi had come to Barcelona, he would have come to Barcelona immediately after leaving PSG, but I think he does not want to come to Barcelona now, so his coming is impossible now. And yes, if this news is true, then we are welcoming Messi to Barcelona.
Barca wants to hand in Messi a legendary treat, that entails being a member of the club before Camp Nou reopening day. The Catalan club are quietly working on this grand inauguration and would be ready to procure the Argentine striker in a deal that's meant to be concluded after next year's world cup. And that's the predetermined time given by the contractors for the finishing of the Spotify camp Nou. So, with the funds ready, Messi would want to accept the honor from Barcelona. Between the trend will as well boost his presence in the football world.
Now, I am not entirely sure how this could happen in an official game. But I know that they could make some sort of special game. Like you know how we see retired players get together and have one more game?
We have seen plenty of retired players keep playing on special exhibition games before, and could happen here again. If that were to ever happen, then we could see Messi show up one more time and play in a special exhibition game for the opening of the new stadium. That wouldn't require him to be signed, and they should definitely avoid signing him, because he is now old and he isn't as good as he used to be and he still worths a lot more just because of his name, that would be that bad. I can't see this as a justified good move.