It's borderline impossible for a specialty player to make the HOF. Think about it, Ray Guy is BY FAR the best punter to have ever played, it took them decades to get him in. Think about how many true kickers are in the HOF, there aren't many. Hester was a return specialist, that didn't do anything else, and one could make the argument that he had a relatively short dominant period. He had 11 return TDs his first two years in the NFL, and in the last 9 years combined had 8 returns scores. While he holds practically every return record, I don't know if the media is going to buy this guy as some can't miss HOFer.
I hope that they do, but if guys like Jerry Kramer, Bob Brown and Kenny Stabler can be kept out of the Hall for decades, then...