Only 280 people have been enshrined in the Pro Football Hall of Fame in 91 years. Enshrinement is only for the best of the best, and it can take years for even great players to receive the honor.
As far as which active players deserve to have their likeness cast in bronze, each one must be considered carefully. Far too often, the label "Future Hall of Famer" is thrown around recklessly when history shows that some great players may not make it.
When we are talking about which players are "guaranteed" to make it into the Hall of Fame, there is another layer of scrutiny. There are plenty of players who are well on their way or on the cusp, but an argument could be made—based on players who haven’t made it in the past—that they don’t deserve the honor.
Since a maximum of seven candidates can be elected into the Hall of Fame each year, there will be a backlog of candidates if we go over that number significantly. There is already a backlog of worthy candidates trying to get in.
The game has also changed over the years, and certain positions are no longer as valuable. There is a reason there isn’t a punter in the Hall of Fame; certain positions just don’t have the required impact on the game to be inducted.
Changes in the value of positions must be taken into consideration, which makes it much harder to guarantee players at certain positions are worthy of the honor.