He is continuing in Dortmund where he stopped in Salzburg. Impressive. I'm sure he feels ready for the next step in his career and another move in summer won't be too early for his development. I doubt he'll get it in 2021 though. With this pandemic and empty stadiums much longer than most clubs planned, I don't think a club can afford him and pay Dortmund's asking price. If the rumors about his release clause in 2022 are true, many top clubs will try to sign him and he'll literally have the agony of choice.
Hopefully, the new president has the finances sorted out until then so Barca can enter the bidding war. Messi will be 35 in 2022 and with the World Cup in Qatar being his big aspiration he might leave Europe after the tournament if he decides to extend his contract at the club.