
A Halti won't necessarily stop him pulling. They are very much a "last resort" when all else has failed.
But you are right to be concerned - he certainly
won't grow out of it on his own. If you don't really get down to working on this he'll just become a bigger, stronger puller.
There have been many threads on here about pulling on the lead in the past - if you do a search I'm sure you'll find many good ideas there.
:)