The new recall rules might give them a better chanceTonga have always had decent players but they are let down by two things, their ill discipline which often leaves them down a player (or 3) and the fact that their really top players will try and play for New Zealand or other wealthy nations.
For those reasons I don’t think they will ever be consistently good, you may have one or two tournaments in 10 where they do well - like Samoa and Fiji.