So, Klose is currently in first place with 16 goals, but Messi with 13 goals and Mbappe with 12 goals are very close to him.
Messi even scored 4 goals out of 13 from penalties.
I read somewhere that Messi stated that he will play in another world cup, if Argentina becomes the world champion. So, Messi will most likely have a good chance to become the top scorer of the world football championships in 4 years.
However, given that he is still a very young and talented striker, and that he will almost certainly appear in 2-3 more world championships, my prediction is that in 8 years Mbappe will become the best scorer in the world football championships and that record will stand for a very long time.
I know there's no bet to put like this (maybe in some gambling houses in UK) but I bet Mbapeé will get to the top in the next World Cup.
Only 4 goals to get to the top, if we consider France will play next world cup and get at least at quarter finals (easy achievement), there's 5 matches to score 4 goals, considering he's the penalty taker, and considering France is going to be the seed and face at least one weaker team, the chances are high.
Another last thing to consider, the next world cup will have 48 teams instead of 32, so there's more probablity to have weaker teams and more goals.