I think Zach's numbers thus far are quite comparable to those of 3 other HOF-locks.
Derrick Brooks - 144 games, 1138 total tackles, 7.90 per game average, 7.5 sacks, 19 INTs, 5 TDs (7 Pro Bowls) (1 Super Bowl)
Junior Seau - 215 games, 1473 total tackles, 6.9 per game average, 50 sacks, 15 INTs, 1 TD (11 Pro Bowls)
Ray Lewis - 113 games, 1094 total tackles, 9.7 per game average, 21 sacks, 20 INTs, 1 TD (4 Pro Bowls) (1 Super Bowl - MVP)
Zach Thomas - 120 games, 1109 total tackles, 9.2 per game average, 11.5 sacks, 15 INTs, 4 TDs (4 Pro Bowls)
If Zach can maintain his current level of play for 3 more years, I'd say he gets inducted. I wouldn't expect him to be a first balot selection, but he'd diffenitely get in eventually.