If they made a sequel to this Jumanji with the same actors playing their video game characters, it's not going to have the same effect as the first one. The whole point is that teenagers are playing as these avatars. If a sequel has new kids playing the game, then The Rock will have a different personality. If it's the same kids playing the game, the sequel will just retread all the same things as the first.
If you ask me, this is best left a one and done situation. Of course, Hollywood does like money, so who knows.